[clang] [Clang] Implement P2864R2 Remove Deprecated Arithmetic Conversion on… (PR #73105)

[Aaron Ballman via cfe-commits]

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@@ -182,6 +182,9 @@ C++2c Feature Support
   This is applied to both C++ standard attributes, and other attributes supported by Clang.
   This completes the implementation of `P2361R6 Unevaluated Strings <https://wg21.link/P2361R6>`_
 
+- Implemented `P2864R2 Remove Deprecated Arithmetic Conversion on Enumerations From
+C++26 <https://wg21.link/P2864R2>`_.
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AaronBallman wrote:

```suggestion
- Implemented `P2864R2 Remove Deprecated Arithmetic Conversion on Enumerations From C++26 <https://wg21.link/P2864R2>`_.
```
This should fix the Sphinx build issues.

https://github.com/llvm/llvm-project/pull/73105