Add additional instructions to use release tarball (apache#198)

docs/running-on-kubernetes.md

@@ -10,7 +10,7 @@ currently limited and not well-tested. This should not be used in production env
 
 * You must have a running Kubernetes cluster with access configured to it using [kubectl](https://kubernetes.io/docs/user-guide/prereqs/). If you do not already have a working Kubernetes cluster, you may setup a test cluster on your local machine using [minikube](https://kubernetes.io/docs/getting-started-guides/minikube/).
 * You must have appropriate permissions to create and list [pods](https://kubernetes.io/docs/user-guide/pods/), [nodes](https://kubernetes.io/docs/admin/node/) and [services](https://kubernetes.io/docs/user-guide/services/) in your cluster. You can verify that you can list these resources by running `kubectl get nodes`, `kubectl get pods` and `kubectl get svc` which should give you a list of nodes, pods and services (if any) respectively.
-* You must [build Spark with Kubernetes support](../resource-managers/kubernetes/README.md#building-spark-with-kubernetes-support) from source.
+* You must have a spark distribution with Kubernetes support. This may be obtained from the [release tarball](https://github.com/apache-spark-on-k8s/spark/releases) or by [building Spark with Kubernetes support](../resource-managers/kubernetes/README.md#building-spark-with-kubernetes-support).
 
 ## Driver & Executor Images