Fix matrix_mautrix_meta_instagram_bridge_permissions_custom to use a dict

Related to spantaleev#3254

Author: spantaleev

docs/configuring-playbook-bridge-mautrix-meta-instagram.md

@@ -56,7 +56,7 @@ If you don't define the `matrix_admin` in your configuration (e.g. `matrix_admin
 You may redefine `matrix_mautrix_meta_instagram_bridge_permissions_default` any way you see fit, or add extra permissions using `matrix_mautrix_meta_instagram_bridge_permissions_custom` like this:
 
 ```yaml
-matrix_mautrix_meta_instagram_bridge_permissions_custom: |
+matrix_mautrix_meta_instagram_bridge_permissions_custom:
   '@YOUR_USERNAME:YOUR_DOMAIN': admin
 ```