Add encryption configuration defaults to Mautrix bridges

Related to #451 (Github Issue).

roles/matrix-bridge-mautrix-facebook/defaults/main.yml

@@ -141,6 +141,17 @@ matrix_mautrix_facebook_configuration_yaml: |
       presence: true
       # Whether or not to update avatars when syncing all contacts at startup.
       update_avatar_initial_sync: true
+      # End-to-bridge encryption support options. These require matrix-nio to be installed with pip
+      # and login_shared_secret to be configured in order to get a device for the bridge bot.
+      #
+      # Additionally, https://github.com/matrix-org/synapse/pull/5758 is required if using a normal
+      # application service.
+      encryption:
+          # Allow encryption, work in group chat rooms with e2ee enabled
+          allow: false
+          # Default to encryption, force-enable encryption in all portals the bridge creates
+          # This will cause the bridge bot to be in private chats for the encryption to work properly.
+          default: false
 
       # Permissions for using the bridge.
       # Permitted values: