docs: Update README
Adds some info about using the script to automate component upgrades, plus some minor cleanup and reformatting.
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.
Adds some info about using the script to automate component upgrades, plus some minor cleanup and reformatting.