kubeadm: add instruction to check kubelet status

kubelet can fail to start due to various reason, e.g mismatching cgroup
drivers. Add this step to save user from having to go back and check when
found etcd cluster is not running successfully.

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

@@ -50,7 +50,7 @@ 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.
@@ -68,6 +68,12 @@ this example.
     systemctl restart kubelet
     ```
 
+    Check the kubelet status to ensure it is running.
+
+    ```sh
+    systemctl status kubelet
+    ```
+
 1. Create configuration files for kubeadm.
 
     Generate one kubeadm configuration file for each host that will have an etcd