diff --git a/docs/configuring-playbook-appservice-double-puppet.md b/docs/configuring-playbook-appservice-double-puppet.md
index 0c0f7077e..8e20494a8 100644
--- a/docs/configuring-playbook-appservice-double-puppet.md
+++ b/docs/configuring-playbook-appservice-double-puppet.md
@@ -14,6 +14,14 @@ To enable the Appservice Double Puppet service, add the following configuration
 matrix_appservice_double_puppet_enabled: true
 ```
 
+### Extending the configuration
+
+There are some additional things you may wish to configure about the service.
+
+Take a look at:
+
+- `roles/custom/matrix-appservice-double-puppet/defaults/main.yml` for some variables that you can customize via your `vars.yml` file. You can override settings (even those that don't have dedicated playbook variables) using the `matrix_appservice_double_puppet_registration_configuration_extension_yaml` variable
+
 ## Installing
 
 After configuring the playbook, run it with [playbook tags](playbook-tags.md) as below: