11.0.0-beta2 release notes

See parent issue for general instructions.

For this specific issue (and other betas and RCs), the release notes are just incremental from beta1. Some of those changes will be significant enough to incorporate into the final 11.0.0 notes; others have early adopters as an audience and will not need to be in the final 11.0.0 release notes.

Release notes draft: https://docs.google.com/document/d/18fMMk1a1zk-gzlyyUjDXEpyJ52gLx21O9K7z...