Add subnet name as a parameter for patching a collection.

Author: arcadiahlyy

src/ServiceManagement/RemoteApp/Commands.RemoteApp/Collection/UpdateAzureRemoteAppCollection.cs

@@ -40,7 +40,7 @@ public class UpdateAzureRemoteAppCollection : RdsCmdlet
 
         [Parameter(Mandatory = false,
             ValueFromPipelineByPropertyName = true,
-            HelpMessage = "For Azure VNets only, the name of the subnet to patch the collection"
+            HelpMessage = "Name of the subnet to move the collection into."
         )]
         public string SubnetName { get; set; }