[DOC] - Expand backup section to include more info

Preliminary Checks

• This issue is not a question, feature request, RFC, or anything other than a bug report. Please post those things in GitHub Discussions: https://github.com/nebari-dev/nebari/discussions

Summary

https://nebari-docs.netlify.app/docs/how-tos/manual-backup/ is not complete right now. We could improve it by adding a few sections.

• Backing up the conda store nfs drive will not restore the conda database. Give info on how to backup and restore the conda store db.
• Existing Argo Workflows history and CronWorkflows will be deleted. You'd need to manually copy CronWorkflows spec down and re-apply.
• Custom Grafana dashboards would need to be backed up manually as well. I'm sure Grafana has some docs on how to do so.
• I'm not sure if copying the jupyterhub database would preserve the CDS Dashboards configuration or not. It also might be important in what order we restore things. E.g. You might need to restore the keycloak users, then the jupyterhub database, but not sure right now.
• I'm not sure if backing up the jupyterhub database is still needed since user info is in keycloak. CDS dashboards info is the only reason I can think of, and I'm not sure if that would work anyway.
• Any custom nebari deployment modifications may require manual steps to re-apply as well
  • using custom cert, etc.

Start with the manual backup page at https://nebari-docs.netlify.app/docs/how-tos/manual-backup/ and verify the backup and restore behavior for the conda store database, Argo Workflows resources, Grafana dashboards, Keycloak users, and JupyterHub data. Resolve the open questions about restore order and custom deployment changes before documenting the procedures. Done means the page clearly covers each manual backup or re-application step and identifies any unsupported or uncertain cases.