Feat: Namespace started with kube- is not allowed

Created by: zackzhangkai

What would you like to be added:

Kubernetes documentation explicitly tells users not to create namespaces that start with kube- - see https://kubernetes.io/docs/tasks/administer-cluster/namespaces/#creating-a-new-namespace where it says:

Note: Avoid creating namespace with prefix kube-, since it is reserved for Kubernetes system namespaces.