kyverno/test/Namespace/policy-namespace.yaml

apiVersion: kubepolicy.nirmata.io/v1alpha1
kind: Policy
metadata :
  name : policy-namespace

spec :
  rules:
    - name: ns1
      resource:
        kind : Namespace
        selector:
          matchLabels:
            LabelForSelector : "namespace"
      mutate:
        patches:
        - path: "/metadata/labels/replaced"
          op: add
          value: "yes"
        - path: "/metadata/name"
          op: replace
          value: "modified-namespace"