Properly format topic subscription command

Author: phillipdwright

articles/event-grid/custom-event-quickstart.md

@@ -82,8 +82,8 @@ The endpoint for your web app must include the suffix `/api/updates/`.
 endpoint=https://$sitename.azurewebsites.net/api/updates
 
 az eventgrid event-subscription create \
-  --source-resource-id "/subscriptions/{subscription-id}/resourceGroups/{resource-group}/providers/Microsoft.EventGrid/topics/$topicname" 
-  --name demoViewerSub 
+  --source-resource-id "/subscriptions/{subscription-id}/resourceGroups/{resource-group}/providers/Microsoft.EventGrid/topics/$topicname" \
+  --name demoViewerSub \
   --endpoint $endpoint
   
 ```