How releases work

Summary

The pieces of a release and how they fit: milestones vs epics vs features, milestone vs candidate vs parent milestone, parent milestones, rejected-before-ship vs broken-after-ship, how an epic joins a milestone, deliverables, releases, candidates, environments and routes, the checklist, gates and enforcement, readiness, waivers, sign-off, promotion (including idempotent re-promotion and CI-reported deployments), holding CI deploys, release contents, and when in-review work completes.