add release cycle and release review steps file

This document is for the project team to use as a reference when we're preparing for a release or review. It describes:

• the release cycle of a specification version
• versions and milestone builds
• purpose and guidelines of a release review
• purpose and guidelines of a progress review

The content summarizes information presented across several Eclipse publications, which are listed in the section, Reference materials.

Questions/considerations:

• I'm not sure this is the best place for the versioning information in the long term, but in the short term it seems acceptable? Suggestions are welcome.
• To compliment this document, I suggest we set up an issue to create an issue template that mirrors this document in checklist form. It should include the minute tasks, like who gets emailed at what email address and what records need to be updated in what interface, which isn't included in this document.