[libc-commits] [libc] [libc][docs][NFC] Rename Maintainers.rst to Maintainers.md (PR #191882)

[Michael Jones via libc-commits]

https://github.com/michaelrj-google commented:

The reason this was an rst file was to match the rest of the docs. As long as the website still works, I'm fine with this change.

https://github.com/llvm/llvm-project/pull/191882