Direct support query submitters to Server Fault

Use the right URL for Server Fault queries tagged Kubernetes, not the
wrong URL for Stack Overflow (which is more about workload / app
development help).

Author: Tim Bannister

.github/ISSUE_TEMPLATE/support.md

@@ -11,7 +11,7 @@ STOP -- PLEASE READ!
 
 GitHub is not the right place for support requests.
 
-If you're looking for help, check [Stack Overflow](https://stackoverflow.com/questions/tagged/kubernetes)
+If you're looking for help, check [Server Fault](https://serverfault.com/questions/tagged/kubernetes).
 
 You can also post your question on the [Kubernetes Slack](http://slack.k8s.io/) or the [Discuss Kubernetes](https://discuss.kubernetes.io/) forum.