Add release notes for Review Board 3.0.16.
Review Request #10815 — Created Jan. 6, 2020 and submitted
This is a fairly large architectural release that focuses on
improvements for repository configuration, giving SCMTools the ability
to define their own repository-related forms, adding custom IDs to
SCMTools and HostingServices, fixing up state preservation and clearing
and validation, and more.
There are API improvements for setting user information and filtering
review requests by branch.
Compatibility with Beanstalk, Bitbucket, and Subversion have been
improved as well.
Built the release notes and checked for building errors, typos, links,
and spelling errors.