admin: new section on user moderation

Also
s/NOTIFY_NEW_SIGN_UPS/SEND_NOTIFICATION_EMAIL_ON_NEW_USER/
See https://codeberg.org/forgejo/forgejo/pulls/1481

docs/admin/config-cheat-sheet.md

@@ -499,7 +499,7 @@ And the following unique queues:
 
 - `DEFAULT_EMAIL_NOTIFICATIONS`: **enabled**: Default configuration for email notifications for users (user configurable). Options: enabled, onmention, disabled
 - `DISABLE_REGULAR_ORG_CREATION`: **false**: Disallow regular (non-admin) users from creating organizations.
-- `NOTIFY_NEW_SIGN_UPS`: **false**: enable email notifications to instance admins on new user sign-up.
+- `SEND_NOTIFICATION_EMAIL_ON_NEW_USER`: **false**: enable email notifications to instance admins on new user sign-up.
 
 ## Security (`security`)
 

docs/admin/index.md

@@ -19,3 +19,4 @@ These documents are targeted to people who run Forgejo on their machines.
 - [Search Engines and robots.txt](./search-engines-indexation/)
 - [Recommended Settings and Tips](./recommendations/)
 - [GPG Commit Signatures](./signing/)
+- [Moderation tools](./moderation/)

docs/admin/moderation.md

@@ -0,0 +1,25 @@
+---
+title: 'Moderation tools'
+license: 'CC-BY-SA-4.0'
+---
+
+Moderation tools are meant to help the Forgejo users and admins cope
+with spam bots and undesirable interactions.
+
+`[admin].SEND_NOTIFICATION_EMAIL_ON_NEW_USER` can be set to `true` on
+small Fogejo instances with an open registration. Such instances are
+subject to occasional spam bots registrations and saves the admin the
+trouble to check on a regular basis. Read more in the [config cheat
+sheet](../config-cheat-sheet/#security-security).
+
+On large instances the moderation team may be too busy with fighting
+spam to handle problematic relationships between users. Self
+moderation tools may help in this case and allow users to block any
+unwanted interaction from another user. Read more in the [user
+blocking guide](../../user/blocking-user/).
+
+To delete a user, including all the repositories or issues they
+created the Forgejo admin can either:
+
+- Use the administration panel of the web interface
+- Use the `forgejo admin user delete --purge` command line. Read more in the [command line documentation](../command-line/#delete).