Add release notes for Review Board 3.0.5.

Review Request #9828 — Created March 22, 2018 and submitted — Latest diff uploaded

Information

Review Board
release-3.0.x
2a00338...

Reviewers

This covers the emergency fixes for bugs introduced by the Gerrit
changes, fixes for API token policies, submit-as with Active
Directory, Bitbucket Server being listed twice, and some other issues
that recently cropped up.

Built the docs. Tested all links and checked for spelling issues and
build errors.