[llvm][docs] Link to correct maintainers file for clang-tools-extra

5eeb3fe moved it from CODE_OWNERS.txt.

Author: DavidSpickett

llvm/Maintainers.md

@@ -428,7 +428,7 @@ Others only have a lead maintainer listed here.
 
 [Clang maintainers](https://github.com/llvm/llvm-project/blob/main/clang/Maintainers.rst)
 
-[Clang-tools-extra maintainers](https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/CODE_OWNERS.TXT)
+[Clang-tools-extra maintainers](https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/Maintainers.txt)
 
 [Compiler-rt maintainers](https://github.com/llvm/llvm-project/blob/main/compiler-rt/CODE_OWNERS.TXT)