Update submission-queue.md

docs/runner/submission-queue.md

@@ -4,6 +4,7 @@ The runner can be configured to add new submissions to a queue, and for this que
 
 By enabling the queue service this will change the webhook process, so that the runner will push the submission to a specified database, and will await a response from the submitter for a few seconds before returning the success screen to the user.
 
+
 ## Setup
 
 Before enabling the queue service you will need a database instance set up which the runner can access. Once your database is set up, you can enable the queue service by configuring the following environment variables:
@@ -15,3 +16,20 @@ Before enabling the queue service you will need a database instance set up which
 | QUEUE_DATABASE_USERNAME        | Used for configuring the user being used to access the database                          |         | root                                        |
 | QUEUE_DATABASE_PASSWORD        | Used for configuring the password used for accessing the database                        |         | password                                    |
 | QUEUE_SERVICE_POLLING_INTERVAL | The amount of time, in milliseconds, between poll requests for updates from the database | 500     |                                             |
+
+Webhooks can be configured so that the submitter only attempts to post to the webhook URL once. 
+
+```.json
+{
+  “outputs”: [
+    {
+      “type”: “webhook”,
+      “name”: “api”,
+      “outputConfiguration”: {
+        “url”: “https://api:9000”,
+        “allowRetry”: false
+      }
+    }
+  ]
+}
+```