Set up for Fall 22

[ml8]

TODO:

• [x] Add sync of new repo
• [x] Remove old admins
• [x] Upgrade to latest JupyterHub version + Helm chart
• [x] Rebuild docker containers with updated packages
• [x] Push release

This also contains an update to the README documenting regular maintenance, including the process for updating between semesters.

[ml8]

All changes are pushed/deployed, so fall should be good for whoever is teaching it.