Update setup-ha-etcd-with-kubeadm.md

It was not clear to me that I had to add the unit file to all nodes and restart the kubelet service. I was stuck wondering why etcd could not connect to the other peers until i realized that kubelet was only running on `HOST-0`.

Remove parantheses.

Improve phrasing.

Update content/en/docs/setup/production-environment/tools/kubeadm/setup-ha-etcd-with-kubeadm.md

Co-authored-by: Tim Bannister <tim@scalefactory.com>

content/en/docs/setup/production-environment/tools/kubeadm/setup-ha-etcd-with-kubeadm.md

@@ -50,7 +50,8 @@ this example.
 
 
 1. Configure the kubelet to be a service manager for etcd.
-
+  
+   {{< note >}}You must do this on every host where etcd should be running.{{< /note >}}
     Since etcd was created first, you must override the service priority by creating a new unit file
     that has higher precedence than the kubeadm-provided kubelet unit file.
 
@@ -270,4 +271,3 @@ Once you have a working 3 member etcd cluster, you can continue setting up a
 highly available control plane using the [external etcd method with
 kubeadm](/docs/setup/production-environment/tools/kubeadm/high-availability/).
 
-