[clang] [docs][clang] Document additional public profile runtime APIs (PR #224424)

[Reid Kleckner via cfe-commits]

https://github.com/rnk approved this pull request.

Looks good to me, but for bonus points, I think we can include all of these "forward declared" APIs in compiler-rt/include/profile/instr_prof_interface.h, which appears to have been added in 2024, so it might post-date these docs.

In that change, you can clean up the docs to point to the interface header, and briefly mention that all APIs can be forward declared if including compiler interface headers is challenging in a build environment.

https://github.com/llvm/llvm-project/pull/224424