deprecate three admission controller (#7363)

Author: CaoShuFeng

docs/admin/admission-controllers.md

@@ -72,9 +72,9 @@ server if Kubernetes is deployed in a self-hosted way.
 
 ## What does each admission controller do?
 
-### AlwaysAdmit
+### AlwaysAdmit (DEPRECATED)
 
-Use this admission controller by itself to pass-through all requests.
+Use this admission controller by itself to pass-through all requests. AlwaysAdmit is DEPRECATED as no real meaning.
 
 ### AlwaysPullImages
 
@@ -86,9 +86,9 @@ scheduled onto the right node), without any authorization check against the imag
 is enabled, images are always pulled prior to starting containers, which means valid credentials are
 required.
 
-### AlwaysDeny
+### AlwaysDeny (DEPRECATED)
 
-Rejects all requests.  Used for testing.
+Rejects all requests. AlwaysDeny is DEPRECATED as no real meaning.
 
 ### DefaultStorageClass
 
@@ -418,15 +418,15 @@ subresource of the referenced *owner* can change it.
 {% assign for_k8s_version="v1.9" %}{% include feature-state-alpha.md %}
 The `PVCProtection` plugin adds the `kubernetes.io/pvc-protection` finalizer to newly created Persistent Volume Claims (PVCs). In case a user deletes a PVC the PVC is not removed until the finalizer is removed from the PVC by PVC Protection Controller. Refer to the [PVC Protection](/docs/concepts/storage/persistent-volumes/#persistent-volume-claim-protection) for more detailed information.
 
-### PersistentVolumeLabel
+### PersistentVolumeLabel (DEPRECATED)
 
 This admission controller automatically attaches region or zone labels to PersistentVolumes
 as defined by the cloud provider (for example, GCE or AWS).
 It helps ensure the Pods and the PersistentVolumes mounted are in the same
 region and/or zone.
 If the admission controller doesn't support automatic labelling your PersistentVolumes, you
 may need to add the labels manually to prevent pods from mounting volumes from
-a different zone.
+a different zone. PersistentVolumeLabel is DEPRECATED and labeling persistent volumes has been taken over by [cloud controller manager](/docs/tasks/administer-cluster/running-cloud-controller/).
 
 ### PodNodeSelector