Update docs/configuring-playbook-bridge-mautrix-bridges.md: add descriptions about configuring bridge permissions

Partially based on docs/configuring-playbook-bridge-mautrix-meta-instagram.md etc.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

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

@@ -19,7 +19,9 @@ There are some additional things you may wish to configure about the bridge befo
 
 ### Configure bridge permissions (optional)
 
-To **configure a user as an administrator for all bridges**, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
+By default any user on your homeserver will be able to use the mautrix bridges. To limit who can use them you would need to configure their permissions settings.
+
+Different levels of permission can be granted to users. For example, to **configure a user as an administrator for all bridges**, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
 
 ```yaml
 matrix_admin: "@alice:{{ matrix_domain }}"
@@ -34,6 +36,10 @@ matrix_mautrix_SERVICENAME_configuration_extension_yaml: |
       '@alice:{{ matrix_domain }}': admin
 ```
 
+This will add the admin permission to the specific user, while keeping the default permissions.
+
+You could also redefine the default permissions settings completely, rather than adding extra permissions. You may wish to look at `roles/custom/matrix-bridge-mautrix-SERVICENAME/templates/config.yaml.j2` to find information on the permission settings and other options you would like to configure.
+
 ### Enable encryption (optional)
 
 [Encryption (End-to-Bridge Encryption, E2BE) support](https://docs.mau.fi/bridges/general/end-to-bridge-encryption.html) is off by default. If you would like to enable encryption, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file: