Document the permissions settings. Distinguish between augmenting and overwriting.

docs/configuring-playbook-bridge-mautrix-signal.md

@@ -23,14 +23,36 @@ Use `!signal unset-relay` to deactivate.
 By default, any user on your homeserver will be able to use the bridge.
 If you enable the relay bot functionality, it will relay every user's messages in a portal room - no matter which homeserver they're from.
 
-If you would like to have a more specific setting of the permissions you can set the permissions as follows (example). For more details see also [mautrix-bridge documentation](https://docs.mau.fi/bridges/python/signal/relay-mode.html)
+Different levels of permission can be granted to users:
+
+* relay - Allowed to be relayed through the bridge, no access to commands;
+* user - Use the bridge with puppeting;
+* admin - Use and administer the bridge.
+
+The permissions are following the sequence: nothing < relay < user < admin.
+
+The default permissions are set as follows:
+```yaml
+permissions:
+  '*': relay
+  YOUR_DOMAIN: user
+```
+
+If you want to augment the preset permissions, you might want to set the additional permissions with the following settings in your `vars.yml` file:
 ```yaml
 matrix_mautrix_signal_configuration_extension_yaml: |
   bridge:
     permissions:
       '@YOUR_USERNAME:YOUR_DOMAIN': admin
-      YOUR_DOMAIN: user
-      '*': relay
+```
+
+This will add the admin permission to the specific user, while keepting the default permissions.
+
+In case you want to replace the default permissions settings **completely**, populate the following item within your `vars.yml` file:
+```yaml
+matrix_mautrix_signal_bridge_permissions: |
+  '@ADMIN:YOUR_DOMAIN': admin
+  '@USER:YOUR_DOMAIN' : user
 ```
 
 You may wish to look at `roles/matrix-bridge-mautrix-signal/templates/config.yaml.j2` to find more information on the permissions settings and other options you would like to configure.