docs/dev/development.rst: Update some testing notes
Don't mention tox. Do mention Docker.
Fix some markup so that sample command are rendered properly.
How to register an account on GitLab. To prevent spam, new accounts are locked until approved by an admin or the approver bot. You can also file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
Don't mention tox. Do mention Docker.
Fix some markup so that sample command are rendered properly.