Complete our release process doc wrt. non-final releases
There are various areas where there aren't very specific instructions when it comes to non-final releases. For example:
XXX: adapt / fork for release candidates. In the meantime, read all this, and skip what does not make sense for a RC.
This is kinda scary for someone who has never RM'ed a non-final release (alpha, beta, RC). We should fix that.
Ideally, someone who's already RM'ed a non-final release would test the resulting updated instructions while RM'ing a real non-final release, before a RM who never did that goes through it.