Update toc.yml for AGC to valid SO tag

Author: ImSkully

articles/application-gateway/for-containers/toc.yml

@@ -130,5 +130,5 @@
   - name: Regional availability
     href: https://azure.microsoft.com/global-infrastructure/services/
   - name: Stack Overflow
-    href: https://stackoverflow.com/questions/tagged/azure-application-gateway-for-containers
+    href: https://stackoverflow.com/questions/tagged/azure-app-gateway-for-containers