[clang] [clang][doc][SYCL] Expand SYCL driver release notes (PR #200449)

[Mariya Podchishchaeva via cfe-commits]

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@@ -945,10 +945,36 @@ OpenMP Support
 
 SYCL Support
 ------------
+- Initial SYCL offload compilation support has been added to Clang. The
+  new ``-fsycl`` flag enables SYCL offloading, producing a SPIR-V device image
+  packaged into the host object. ``-fsycl-device-only`` and
+  ``-fsycl-host-only`` restrict compilation to the device or host side
+  respectively. (#GH117268)
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Fznamznon wrote:

That GH number usually indicates a related GitHub issue in llvm-project repo, not the PR fixing it.

https://github.com/llvm/llvm-project/pull/200449