Update index.yml

-------
cc: @SyntaxC4

Author: msangapu-msft

articles/app-service/index.yml

@@ -7,7 +7,7 @@ metadata:
   title: Azure App Service documentation
   description: Host websites, web apps, RESTful APIs, and mobile back ends in Azure App Service. Find quickstarts, tutorials, and samples to help you succeed with App Service.
   ms.topic: landing-page
-  ms.author: msangapu
+  ms.author: app-svc-docs
   ms.service: app-service
   ms.date: 01/31/2023