Don't get me wrong, it's not like there's no overlap, but I'm looking for the equivalent of "Clean Code" for technical writing.
Anyway, it's not that none of these principles apply, it's just that there are almost certainly many tweaks here and there and additional tips for people writing technical documentation - for example, almost no one sits down and reads the documentation for a library from "front to back", it is usually used in segments, which has implications about what you can expect your reader to know, and about how important navigation and organization of the document are.
These are just some things that I've noticed as a consumer and producer of documentation, and I don't know that I even have good answers to most of them.
(I hate to make it seem like I'm arguing the point that these more general writing guides are not good, I just want to clarify the kind of thing I'm looking to improve, for myself.)
As an aside I like the article How to Write Articles and Essays Quickly and Expertly[0] that was posted here a couple months back as well.
[0] www.downes.ca/post/38526
"The US, a large north-american country,...".