[clang-tools-extra] [clang-tidy] bugprone-unused-return-value config now supports regexes (PR #82952)

[Piotr Zegar via cfe-commits]

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

LGTM, but update also check documentation, simply put there default config so user could easily copy it change, and add new functions. And mention that this support regexp.

https://github.com/llvm/llvm-project/pull/82952