kube-prometheus: update etcd info

Resolves issue #1629 in this repository.

examples/minikube.jsonnet

@@ -1,6 +1,7 @@
 local kp =
   (import 'kube-prometheus/kube-prometheus.libsonnet') +
   (import 'kube-prometheus/kube-prometheus-kubeadm.libsonnet') +
+  // Note that NodePort type services is likely not a good idea for your production use case, it is only used for demonstration purposes here.
   (import 'kube-prometheus/kube-prometheus-node-ports.libsonnet') +
   {
     _config+:: {