Release notes from a changelog

A pile of merged changes that needs to become an announcement.

Write release notes from the changes below. Group them by what the user gets, not by component. Lead with the one thing most people will care about. Drop anything invisible to users, and spell out what any breaking change means for someone who has to act on it.

Changes:

Launch and comms. Getting a release out and told: launch plans, go / no-go, release notes, deprecations, post-launch retros.