Update overview.md

Author: tomaschladek

articles/communication-services/concepts/interop/virtual-visits/overview.md

@@ -1,6 +1,6 @@
 ---
 title: Overview of virtual appointments with Azure Communication Services
-description: Learn concepts for virtual appointments applications
+description: Learn concepts for virtual appointments applications.
 author: tchladek
 manager: chpalm
 services: azure-communication-services