clean.sh shoud check docker command whether exist

[huxiaoliang]

The reset process does not clean your kubeconfig files and you must remove them manually.
Please, check the contents of the $HOME/.kube/config file.
removed '/root/.kube/config'
removed '/etc/kubernetes/kubeadm-config.yaml'
removed '/etc/kubernetes/tke-authz-webhook.yaml'
removed '/etc/kubernetes/known_tokens.csv'
removed '/etc/kubernetes/scheduler-policy-config.json'
removed directory '/etc/kubernetes/pki'
removed '/etc/kubernetes/director-manager/director-manager.conf'
removed directory '/etc/kubernetes/director-manager'
removed directory '/etc/kubernetes/manifests'
removed directory '/etc/kubernetes'
removed directory '/var/lib/kubelet'
removed directory '/var/lib/etcd'
removed directory '/var/lib/cni'
removed '/etc/cni/net.d/00-galaxy.conf'
removed '/etc/cni/net.d/multus/20-tke-bridge.conflist'
removed directory '/etc/cni/net.d/multus'
removed directory '/etc/cni/net.d'
removed directory '/etc/cni'
./clean: line 39: docker: command not found
root@VM-32-11-ubuntu:~#