Added notes in ReleaseNote doc

Author: mdfazlay

clang/docs/ReleaseNotes.rst

@@ -1309,6 +1309,8 @@ OpenMP Support
   mappers, by using compiler-generated default mappers for the outer structs for
   such maps.
 - Deprecation warning has been emitted for deprecated delimited form of ``declare target``.
+- Added parsing and semantic analysis support for the 'need_device_addr' 
+  modifier in the 'adjust_args' clause.
 
 Improvements
 ^^^^^^^^^^^^