Add release notes for Review Board 4.0.2.
Review Request #2422 — Created March 3, 2022 and updated
This is a small release fixing a few bugs with GitLab, Markdown, Subversion, and cookies. It also improves performance with some common queries and introduces a feature for adding known safe URL protocols for Markdown rendering. Testing Done: Built the docs. Checked for build errors, spelling errors, and bad links. Reviewed at https://reviews.reviewboard.org/r/11660/