Undocumented supported apps

[joshtrichards]

Some supported apps lack documentation of any sort in the Admin Manual.

• Circles
• Collaborative tags
• First Run Wizard
• Full text search
• Group folders
• Guests
• Monitoring
• Announcements
• Notifications
• Photos
• Recommendations
• Related resources
• SharePoint Backend
• Suspicious Login
• SSO & SAML authentication
• Social sharing
• Terms of service
• Two-Factor backup codes
• Two-Factor WebAuthn (replaces U2F)
• Talk
• ONLYOFFICE
• Global Site Selector
• Mail

The above should probably each have at a minimum:

• a brief page/section under Configuration (or elsewhere if more appropriate)
• a section in the occ commands chapter (where applicable)

The following don't have much (if any) in the way of admin facing settings/commands, but a brief paragraph mentioning them in the Admin Manual seems appropriate (since they're supported and/or shipped apps). At a minimum describing "What this app does":

• Deck
• Comments
• Contacts Interaction - Collect recent contact interactions server#19075
• Data Request
• Nextcloud Announcements
• PDF Viewer
• Share by Mail
• Calendar (distinct from CalDAV)
• Contacts (distinct from CardDAV)
• Lookup Server Connector

TODO:

• Create dedicated issues for each of the above apps and edit this issue with links to them

[joshtrichards]

WIP (unmerged) docs for Circles found in #6220 & #10420