Add cancel a maintenance window documentation

hugo/content/en/incident_response/status_pages/_index.md

@@ -224,6 +224,16 @@ You can post updates if plans change or reschedule the maintenance window as nee
 
 **Note**: Each status page supports a maximum of 100 scheduled or in-progress maintenance windows at a time.
 
+### Cancel a maintenance window
+
+To cancel a scheduled maintenance window before it starts, open the maintenance notice, click the three-dot icon, and select **Cancel Maintenance**. Confirm the cancellation in the dialog that appears.
+
+{{< img src="incident_response/status_pages/cancel-maintenance.png" alt="Cancel Maintenance confirmation dialog for a scheduled maintenance window" style="width:60%;" >}}
+
+Canceling a maintenance window removes it from **Upcoming Maintenance** on the status page. This action cannot be undone.
+
+**Note**: An in-progress maintenance window can't be canceled.
+
 ### Backfill a maintenance window
 
 Backfilled maintenance windows allow you to retroactively document planned downtime that was not previously announced. Each update can be assigned its original timestamp, so the maintenance timeline appears accurately in your uptime history.