[keycloak-user] Updated release cadence

[Stian Thorgersen]

As we've started working in 3 week sprints we are considering a new release
model for Keycloak.

What we are considering is doing a Beta release for every sprint, then for
every 4th sprint (each quarter) we plan to do a Final release.

For a beta release existing features will be considered stable, while new
features may not be ready for prime time. The recommendation will still be
to upgrade to always update to the latest release to receive the latest
security fixes and other fixes.

However, care should be taken before using new features in production until
a Final release is available.

Thoughts?