Add release notes for Djblets 3.2.
Review Request #12819 — Created Jan. 30, 2023 and submitted
This is a small feature enhancement release, focusing on some
forward-looking improvements for the API, enhancements for unit tests
and deprecation handling, and functionality needed to make use of
integrations on namespaced URLs.
Built the release notes. Checked for build errors, spelling errors,
and bad links.