While these are three unrelated words, they share some characteristics: all are produced by modifying existing words in particular ways that are fairly standard.

You're right that a documenter would be one who documents; in general, adding "-r" or "-er" to a verb very often means someone who often does that verb. Your automated spell-checker doesn't have enough of a vocabulary to tell that automatically, though.

Your intuition about "web-mistress" being related to "webmaster" is also correct. But in compound words using "master", substituting "mistress" is usually not going to make anyone* think of the modern slang usage of "mistress" on its own, since the other words qualify the meaning to be a particular sort of master or mistress… and that almost always means starting from the most basic and literal sense of the word, which is still generally known by native speakers. So this coined word means nothing other than a female webmaster. (It's unlikely to be a formal job title; rather, it's most likely a somewhat whimsical title taken on by the lady herself. This sort of playful self-naming is fairly common among geeks, especially those who work more or less independent of conventional job structures.)

"Cabalesque" has a rather uncommon productive suffix, "-esque" (which means "like" or "in the manner of", and is often separated with a hyphen to make it easier to distinguish). Given that, and the way "cabal" can mean "a small group of people who work together secretly" (MW), "cabalesque knowledge" means something like "cryptic knowledge like that of some old secret societies, carefully isolated from outsiders". (Per Nelson, it can especially refer to highly specialized technical knowledge that has never been shared with those outside a small group, whether intentionally trying to keep it secret or simply not putting effort into sharing that knowledge.)

_{*Except amateur comedians on the Internet, anyway.}

Web-mistress does mean nothing more, and nothing less than web-master. It suggests the person may be female, but given that it occurs in a list of examples (with an implicit etc), it does not prescribe that the person is female.

He is pointedly using web-mistress to emphasise the notion that a web-master can just as easily be female. His message is about the joy he takes in the fact that his code is available to all, and that he despises artificial barriers.

Rusty Russel is known for being a particularly fine human. That is how he got the Rusty Wrench Award named after him. Like most decent people (AFAICT) he is opposed to sexism, and in favour of diversity. Quietly and without being particularly in your face about. See a couple of tweats 1, 2 that just touch on diversity.

As such I assert that he may have been attempting to counter the gender stereotype of all people in IT being men. After all the male word web-master is used so much, he can balance out some of the uses with the female web-mistress. Thus being more inclusive of women in IT.

Nathan Tuggy gives a good breakdown of these words. Concerning cabal:

The word does originally come from kabbalah, and specifically from its French form, cabale. Kabbalah is a form of Jewish mysticism traditionally taught only to adult Jews with in-depth knowledge of the Torah. Mostly it's just philosophy and metaphysics, but in some Jewish stories, rabbis who were deeply knowledgable in kabbalah could recite the secret names of God to wield a fraction of His power, summoning angels and demons, creating living servants called golems from clay, or doing other things which might be considered magic. So a cabal became a conspiracy to control powerful, secret knowledge.

Cabal's popularity grew with the formation of the Cabal Ministry, a group of powerful advisors to the King Charles II of England during the early 1670s. They were seen as secretly wielding political power, essentially making themselves the "power behind the throne". It so happened that the initials of the five men's names spelled out the word cabal, and so the word became associated specifically with secretive political factions.

So cabalesque, or cabal-esque, implies both powerful knowledge kept hidden from the public and small groups of privileged people keeping political power to themselves. In my reading, this passage is using both senses of the term. The author is packing a lot of meaning into one word.

Not directly related to your questions but I would note that the open source/free software community tends to communicate in a fairly informal style.

After some searching I believe the source of the quote in your question to be an interview related to Linux kernel development.

documenter: Why does this word show as having a spelling mistake? I think I can write it similar to a "writer" being "one who writes". Why can't a "documenter" be "one who documents"

It can be but it's not an especially common construction. Spell checkers do not have every valid word in them. Also what words are valid and acceptable depends on who you ask, some words are seen as "slang" or "informal" and are unlikely to be used in a formal context.

web-mistress: I have no clue exactly what this job title means? What are the roles and responsibilities of a "web-mistress", and what are the activities they are involved in routinely? Even though a quick google shows web-mistress to be a female webmaster, I believe this is hardly the job title any company would be giving to its employees. It sounds and implies slang use of "Mistress".

I think it would be pretty uncommon to see this as an actual job title. I think Rusty is deliberately using a female variant here to emphasise that he doesn't think computing should be a men-only world.

cabalesque: This is another word which even Google can't find. I guess it's Spanish or a derived word from other languages. Can you help me understand the probable meaning of this word as used in the context above?

The term "cabal" is generally used to refer to a real or perceived group of people with knowledge and/or power (and in many cases knowledge is power, if you don't know how to do something it's hard to actually do it). There is an (often false) implication that they are being deliberately closed and secretive about it (more likely they are just too busy to help out with newbie questions).

Unfortunately software is usually under-documented. Combine this with a small number of people doing a particular thing with the software (lots of people use the kernel, but a much smaller number do kernel development and an even smaller number do development related to a particular feature) and you can very easily get into a situation where the knowledge on how to do something only exists in a small group of peoples heads. To outsiders this group can feel like a cabal.

I believe this is what Rusty was referring to when he talked of "cabalesque knowledge".

This is not an actual answer, but lists usage of the word cabalesque in other passages around the world for the interested readers. Regarding webmistress, I believe in addition to his implications about gender-neutrality and diversity, Rusty given to his sense of humour was also referring to both male and female lazy-programmers in IT with an intended pun, referring them as web-mistress humorously in an un-explicit way as webmistress is never used in technical literature (server administration) instead the gender neutral webmaster is always used. It may sound wrong, but its how the IT culture is given the current attrition and unemployment rate. Web-mistress has been used as a paronomasia by Rusty, although webmistress being a non-polysemous word.

1. cabalesque conspiracy: Simply put, we can be fairly certain of Jesus’ existence and at least some of the specifics of His ministry because it did not “spring full-grown from the head of Zeus” in some cabalesque conspiracy, and dozens of documents from dozens of sources - from different regions and different time periods - “overlap” with enough accuracy to reveal a fairly accurate picture of at least some, if not much, of His ministry.

2. cabalesque group: About that effort and one's since. There's been a lot of money poured in. There's even mention of a cabalesque group that bankrolls the machine.

3. cabalesque vibe:No, it was done before hand, the reason why, I really like the way Ritalin sounds, it has this kind of dark cabalesque sort of vibe to it in the sense of these things being so easily disseminated to children and the effect that has on a lot of children, so it was something that I wanted to try just to have an understanding of it and I wanted to talk to some kids that were on it and then when we found out we couldn't necessarily use the name Ritalin or any form of the name like R.I.T.A.L.I.N because of convolution, it became apparent to me that the only way around it, because I still wanted to somehow connect Ritalin to the name because I wanted people to talk about it.

4. cabalesque influence:As a mom, I’m driven to creating a sense of inner character and beauty in both of my children, male and female. In order to do this, I think it’s important to keep them from the dominant media culture as much as possible, as long as possible. This especially applies to the cabalesque influence of the Disney Princess regime and the Barbie empire. Both of the aforementioned perpetuate unrealistic physiques for girls and shuttle them into cattle shoots the feed the girls into cookie cutter versions of who they should become. This may sound extreme, but if you doubt my mentality, take a few days to breeze through Packaging Girlhood. It makes a pretty good case for the fact that there genuine intent in the crafting of marketing schemes to produce ultimate consumers. Or read this wonderful letter petitioning Pixar to create an un-Disney movie with a female protagonist to get a sense of the need for more.

5. cabaret + burlesque: “It’s cabaret, it’s burlesque, it's cabalesque. Do you dare to step inside?” La Fiesta brings to you the best and finest of CABARET and BURLESQUE (CABALESQUE) in Sydney - Be entertained and enchanted by a variety show of exotic dances, comedy and songs performed on stage by professional international and national artists clad with sexy dazzling costumes, who will recreate for you the amazing spirit of those sensual French, Parisian nights.

6. cabalesque style: Not surprisingly, low performance was associated with a “charismatic” style of leadership, a “cabalesque” style of management, senior managers who were preoccupied with their own maintenance needs, and under-developed and emasculated middle managers, with the ultimate taboo being to challenge senior management; there was also high senior management turnover. The performance of the low performing trusts serves to illustrate aspects of the dark side of charisma.

7. cabalesque fashion: Both of these anime deals with similar themes as well as being shounen -type animes. Both of the main characters have a similar tragic past and as the storyline develops fragments of that past piece themselves together. They also both deal with religion in a similar Cabalesque fashion as both the main characters possess and develop their unique abilities in accordance.

8. cabalesque relationship: A two hundred year old, well documented conspiracy that many prominent people believe still exists was reproduced with embellishments of fiction under a heavily anti-Jewish slant (the original conspiracy was dominated by Jewish financiers too) as 'Protocols of the Elders of Zion', a nearly untraceable manuscript which was pieced together, it seems, from various other pieces of literature that had equally reported Adam Weishaupt's Illuminist Manifesto. Post WWI the manuscript was denounced in a British 'establishment' newspaper, the ownership of which was held IN the Jewish dominated financial elite and their cabalesque relationship with the Crown, and little attention was paid.