[OpenMP] Add OMPT release note

OMPT release note addition for LLVM 17

Differential Revision: https://reviews.llvm.org/D156191

Author: mhalk

openmp/docs/ReleaseNotes.rst

@@ -28,3 +28,4 @@ Non-comprehensive list of changes in this release
   ``libc`` interface, see this `example
   <https://github.com/llvm/llvm-project/blob/main/openmp/libomptarget/test/libc/host_call.c>`_.
 - Fixed the implementation of ``omp_get_wtime`` for AMDGPU targets.
+- Added vendor agnostic OMPT callback support for OpenMP-based device offload.