[clang-tools-extra] [clang-tidy] fix incorrect argument names in documentation for ExtraArgs and ExtraArgsBefore (PR #120963)

[Nicolas van Kempen via cfe-commits]

nicovank wrote:

Sync with [ClangTidyMain.cpp](https://github.com/llvm/llvm-project/blob/d36836de0183b9b1939cc679d153e3b313e55c76/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp#L57-L58)?

https://github.com/llvm/llvm-project/blob/d36836de0183b9b1939cc679d153e3b313e55c76/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp#L57-L58

https://github.com/llvm/llvm-project/pull/120963