update kubeadm reset (#11734)

* update kubeadm reset

The reset process does not  clean up iptables rules , we should do so manually.

* add empty line and end with :

content/en/docs/setup/independent/create-cluster-kubeadm.md

@@ -545,6 +545,12 @@ Then, on the node being removed, reset all kubeadm installed state:
 kubeadm reset
 ```
 
+The reset process does not reset or clean up iptables rules or IPVS tables. If you wish to reset iptables, you must do so manually:
+
+```bash
+iptables -F && iptables -t nat -F && iptables -t mangle -F && iptables -X
+```
+
 If you wish to start over simply run `kubeadm init` or `kubeadm join` with the
 appropriate arguments.