[llvm] [docs] Document which online sync-ups are no longer happening (PR #89361)

[Sander de Smalen via llvm-commits]

https://github.com/sdesmalen-arm approved this pull request.

These changes look fine to me. I can indeed confirm the Scalable Vectors & Arm SVE sync-ups are indeed no longer happening.

Just to be sure, did you build the HTML page to confirm that the table is rendered as expected?

https://github.com/llvm/llvm-project/pull/89361