Update release notes for m92 cut, m93 begin

Change-Id: I216fa16d6dfd57214def9099cb3fa1b5cb281f23
Docs-Preview: https://skia.org/?cl=411299
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/411299
Reviewed-by: Heather Miller <hcm@google.com>
Commit-Queue: Heather Miller <hcm@google.com>
2 files changed