The documentation lives here: https://github.com/python/cpython/blob/d6cf05b5d00abbfdf9008d646c14c6ef7c83b61a/Doc/howto/perf_profiling.rst

Before #136461, cpython only had support for Linux perf profiling. But with this PR it now supports both Linux and macOS through samply. I updated the documentation to include this, but it's not super great currently because previously it was written with the assumption that it was only supported by Linux perf. So it would be good to restructure this doc in a better way, and add more information related to macOS profiling using samply.

Also samply supports both perf modes so it would be good to clarify when to use them.

cc @pablogsal @hugovk