Mention group deletion

All groups where the user is the sole owner will be deleted with the "Delete user and contributions" option.
The "Delete user" option is not available if the user has groups where he is the sole owner.

doc/user/profile/account/delete_account.md

@@ -32,8 +32,10 @@ As an administrator, to delete a user account:
 1. On the left sidebar, select **Overview > Users**.
 1. Select a user.
 1. Under the **Account** tab, select:
-   - **Delete user** to delete only the user but maintain their [associated records](#associated-records).
-   - **Delete user and contributions** to delete the user and their associated records.
+   - **Delete user** to delete only the user but maintain their [associated records](#associated-records). You can't use this option if
+     the selected user is the sole owner of any groups.
+   - **Delete user and contributions** to delete the user and their associated records. This option also removes all groups (and
+     projects within these groups) where the user is the sole direct Owner of a group. Inherited ownership doesn't apply.
 
 WARNING:
 Using the **Delete user and contributions** option may result in removing more data than intended. See
@@ -60,7 +62,7 @@ When deleting users, you can either:
 An alternative to deleting is [blocking a user](../../admin_area/moderate_users.md#block-a-user).
 
 When a user is deleted from an [abuse report](../../admin_area/review_abuse_reports.md) or spam log, these associated
-records are always removed. This includes any groups of which the user is the only user with the Owner role.
+records are always removed.
 
 The deleting associated records option can be requested in the [API](../../../api/users.md#user-deletion) as well as
 the Admin Area.