clang-format release notes: Document the improvement with the AlwaysBreakAfterReturnType option

See https://reviews.llvm.org/D69573

Author: sylvestre

clang/docs/ReleaseNotes.rst

@@ -462,6 +462,8 @@ clang-format
     const x = foo ?? default;
     const z = foo?.bar?.baz;
 
+- Option ``AlwaysBreakAfterReturnType`` now manages all operator functions.
+
 libclang
 --------