docs: add missing notification config details

crates/cli/README.md

@@ -100,6 +100,16 @@ This is the address and port that your reverse proxy should route traffic to.
 - **addr** - the IP address the server should bind to
 - **port** - the IP port the server should bind to
 
+#### notification
+
+The server should be able to notify the user when manual intervention is required.
+Currently this is only available via sending a Webhook message.
+
+- **type** - one of `None` or `Webhook`
+- **webhook** - the URL to POST the notification to
+
+See [Notifications](#notifications) for more details.
+
 #### webhook
 
 Your forges need to know where they should route webhooks to. This should be