Revise etcd task prerequisites to remove playground envs

The etcd operation and maintenance job is not supposed to
run on the playground environments.

Author: tengqm

content/en/docs/tasks/administer-cluster/configure-upgrade-etcd.md

@@ -14,7 +14,11 @@ weight: 270
 
 ## {{% heading "prerequisites" %}}
 
-{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
+You need to have a Kubernetes cluster, and the kubectl command-line tool must
+be configured to communicate with your cluster. It is recommended to run this
+task on a cluster with at least two nodes that are not acting as control plane
+nodes . If you do not already have a cluster, you can create one by using
+[minikube](https://minikube.sigs.k8s.io/docs/tutorials/multi_node/).
 
 <!-- steps -->