[clang] [clang][doc][SYCL] Add SYCL driver and device library release notes to ReleaseNotes.md (PR #211949)

[Alexey Bader via cfe-commits]

https://github.com/bader commented:

@srividya-sundaram, this is still a draft. I'm assuming that this is version is final and ready for review. Please, covert to PR before requesting reviews to make it explicit.

@mdtoguchi, @KseniyaTikhomirova, FYI.

https://github.com/llvm/llvm-project/pull/211949