Add more details about workflow_run (#531)

Author: programmer04

content/actions/reference/events-that-trigger-workflows.md

@@ -655,6 +655,10 @@ on:
 
 {% data reusables.webhooks.workflow_run_desc %}
 
+| Webhook event payload | Activity types | `GITHUB_SHA` | `GITHUB_REF` |
+| --------------------- | -------------- | ------------ | -------------|	
+| [`workflow_run`](/webhooks/event-payloads/#workflow_run) | - n/a | Last commit on default branch | Default branch |	
+
 If you need to filter branches from this event, you can use `branches` or `branches-ignore`.
 
 In this example, a workflow is configured to run after the separate “Run Tests” workflow completes.