[clang-tools-extra] [clang-tidy] Add misc-shadowed-namespace-function check (PR #168406)

[Baranov Victor via cfe-commits]

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@@ -0,0 +1,63 @@
+.. title:: clang-tidy - misc-shadowed-namespace-function
+
+misc-shadowed-namespace-function
+================================
+
+Detects free functions in the global namespace that shadow functions declared 
+in other namespaces. This check helps prevent accidental shadowing of namespace
----------------
vbvictor wrote:

```suggestion
Detects free functions in the global namespace that shadow functions declared 
in other namespaces.

This check helps prevent accidental shadowing of namespace
```

https://github.com/llvm/llvm-project/pull/168406