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

[Aaron Puchert via cfe-commits]

aaronpuchert wrote:

Yes, it doesn't seem to build the docs. The Windows failure looks unrelated:
```
llvm-lit.py: C:\_work\llvm-project\llvm-project\llvm\utils\lit\lit\llvm\config.py:312: fatal: Couldn't find the include dir for Clang ('c:\_work\llvm-project\llvm-project\build\bin\clang.exe')
```

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