[clang] [NFC][analyzer] Document configuration options (PR #135169)

[Balazs Benics via cfe-commits]

https://github.com/steakhal commented:

Thank you for proposing this. It looks really good already.
The code looks nice and dense, and the output also looks wonderful.
I had some design questions and a few remarks on the testing and error handling.

Good job.

https://github.com/llvm/llvm-project/pull/135169