[clang] [Clang] Add release note for pointer overflow optimization change (PR #122462)

[Hans Wennborg via cfe-commits]

================
@@ -58,6 +58,26 @@ code bases.
   containing strict-aliasing violations. The new default behavior can be
   disabled using ``-fno-pointer-tbaa``.
 
+- Clang will now more aggressively use undefined behavior on pointer addition
----------------
zmodem wrote:

Could we add a motivating example to show this is not about pedantry but is useful for removing redundant checks?

https://github.com/llvm/llvm-project/pull/122462