GitLab is used only for code review, issue tracking and project management. Canonical locations for source code are still https://gitweb.torproject.org/ https://git.torproject.org/ and git-rw.torproject.org.
At https://tb-manual.torproject.org/ we should add links to our existing threat-modeling documents. This will help users understand when they need to use a higher security setting level.
As suggested by emmapeel in this pull request: https://github.com/torproject/manual/pull/12