[clang] [clang][analyzer][doc] Migrate user-related docs from HTML to RST (PR #97034)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

I'm really happy to see that this duplicated documentation is finally cleaned up after so many years :partying_face:

I added a few minor remarks in inline comments, but the change looks good overall.

As we discussed privately, this change should be (mostly) limited to the format changes, and then separate follow-up commit should eliminate the outdated content (and, perhaps, add new information if that's necessary). I'll update the PR description to emphasize this.

https://github.com/llvm/llvm-project/pull/97034