Mention k8s in issue template
<!--- Include as many relevant details about the environment you experienced the bug in -->
* Docker version `docker version` (e.g. Docker 17.0.05 ):
+* Are you using Docker Swarm or Kubernetes (FaaS-netes)?
+
* Operating System and version (e.g. Linux, Windows, MacOS):
-* Link to your project:
+* Link to your project or a code example to reproduce issue:
