[clang] [clang-tools-extra] Fix cross-references in Clang attribute reference (PR #142967)

[Erich Keane via cfe-commits]

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

I have no idea about documentation formats ;)  @AaronBallman might know better than I, but nothing that LOOKS wrong here.

https://github.com/llvm/llvm-project/pull/142967