Release Notest update

Author: Chandra Ghale

clang/docs/ReleaseNotes.rst

@@ -1281,6 +1281,8 @@ OpenMP Support
 - Changed the OpenMP DeviceRTL to use 'generic' IR. The
   ``LIBOMPTARGET_DEVICE_ARCHITECTURES`` CMake argument is now unused and will
   always build support for AMDGPU and NVPTX targets.
+- Added support for combined masked constructs  'omp parallel masked taskloop',
+  'omp parallel masked taskloop simd','omp masked taskloop' and 'omp masked taskloop simd' directive.
 
 Improvements
 ^^^^^^^^^^^^