support update resource (#5)

Author: dongjiang1989

hack/deployment/webhook/mutatingwebhookconfiguration.yaml

@@ -18,7 +18,7 @@ webhooks:
         path: "/mutate"
         port: 443
     rules:
-      - operations: ["CREATE"]
+      - operations: ["CREATE","UPDATE"]
         apiGroups: [""]
         apiVersions: ["v1"]
         resources: ["pods"]