APINotes documentation is poor

[rauhul]

the documentation here https://clang.llvm.org/docs/APINotes.html does not include all of the options and doesn't explain the existing options well enough to use without guidance.

I found this gist more helpful than the official documentation: https://gist.github.com/stuartcarnie/b0ff219c712a25ca46d154f5d0dbc3f3