Review our release process + enrich release lead's role

[imath]

A message from @espellcaste about the fact we need to wait for a milestone to get its first stable version released to start working on next milestone made me think we should consider doing just like WordPress, see:
​https://make.wordpress.org/core/handbook/about/release-cycle/releasing-major-versions/#release-candidate

Following the first release candidate a branch for the release can be created so that early work on trunk can begin for the next release.

I also think Release leads should:

1. Decide about the release schedule.
2. Define bug/enhancement/task priorities for the milestone.

Priorities would be the things we absolutely need to include into the milestone. I believe this would help us to communicate early about what users can expect from a release.

• Create a release branch right after RC1
• Add 2 more responsibilities to Release Leads

Trac ticket: ​https://buddypress.trac.wordpress.org/ticket/9204

[espellcaste]

+++

[vapvarun]

Having release leads to set schedules and priorities will help us communicate better and meet user expectations. This will make our development process smoother and faster.
+++