Add documentation for 'occ user:keys:test' command

Signed-off-by: Marcel Müller <[email protected]>

admin_manual/configuration_server/occ_command.rst

@@ -1325,6 +1325,8 @@ report showing how many users you have, and when a user was last logged in::
   user:report                         shows how many users have access
   user:resetpassword                  Resets the password of the named user
   user:setting                        Read and modify user settings
+  user:keys:test                      Verify that the stored public key matches
+                                      the stored private key
 
 
 You can create a new user with their display name, login name, and any group