[clang] [clang-tools-extra] [llvm] [clang] Introduce diagnostics suppression mappings (PR #112517)

[Aaron Ballman via cfe-commits]

================
@@ -0,0 +1,92 @@
+============================
+Warning suppression mappings
+============================
+
+.. contents::
+   :local:
+
+Introduction
+============
+
+Warning suppression mappings enables users to suppress clang's diagnostics in a
+per-file granular manner. Enabling enforcement of diagnostics in specific parts
+of the project, even if there are violations in dependencies or other parts of
+the codebase.
----------------
AaronBallman wrote:

```suggestion
Warning suppression mappings enable users to suppress Clang's diagnostics in a
per-file, granular manner. Enabling enforcement of diagnostics in specific parts
of the project, even if there are violations in dependencies or other parts of
the codebase.
```
Same issue here understanding the last sentence. Whatever you decide for above can be replicated here.

https://github.com/llvm/llvm-project/pull/112517