Update to document date

Updating document date

Author: apwestgarth

articles/azure-stack/azure-stack-app-service-release-notes-update-three.md

@@ -13,7 +13,7 @@ ms.workload: na
 ms.tgt_pltfrm: na
 ms.devlang: na
 ms.topic: article
-ms.date: 08/15/2018
+ms.date: 08/20/2018
 ms.author: anwestg
 ms.reviewer: brenduns