[FOLD] add release note

Author: sdkrystian

clang/docs/ReleaseNotes.rst

@@ -574,6 +574,8 @@ Bug Fixes to C++ Support
   (#GH95854).
 - Fixed an assertion failure when evaluating an invalid expression in an array initializer. (#GH112140)
 - Fixed an assertion failure in range calculations for conditional throw expressions. (#GH111854)
+- Clang now correctly ignores previous partial specializations of member templates explicitly specialized for
+  an implicitly instantiated class template specialization. (#GH51051)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^