Update documentation about alpha provisioning.

docs/user-guide/persistent-volumes/index.md

@@ -547,7 +547,8 @@ and need persistent storage, we recommend that you use the following pattern:
   - If the user provides a storage class name, and the cluster is version 1.4 or newer, put that value into the `volume.beta.kubernetes.io/storage-class` annotation of the PVC.
     This will cause the PVC to match the right storage class if the cluster has StorageClasses enabled by the admin.
   - If the user does not provide a storage class name or the cluster is version 1.3, then instead put a `volume.alpha.kubernetes.io/storage-class: default` annotation on the PVC.
-    - This will cause a PV to be automatically provisioned for the user with sane default characteristics on some clusters.  
+    - This will cause a PV to be automatically provisioned for the user with sane default characteristics on some clusters with Kubernetes up to 1.5.
+    - In Kubernetes 1.6, a default storage class will be used to provision a volume for such PVC.
     - Despite the word `alpha` in the name, the code behind this annotation has `beta` level support.
     - Do not use `volume.beta.kubernetes.io/storage-class:` with any value including the empty string since it will prevent DefaultStorageClass admission controller
       from running if enabled.
@@ -556,5 +557,5 @@ and need persistent storage, we recommend that you use the following pattern:
   PVCs).
 - In the future, we expect most clusters to have `DefaultStorageClass` enabled, and to have some form of storage available.  However, there may not be any
   storage class names which work on all clusters, so continue to not set one by default.
-  At some point, the alpha annotation will cease to have meaning, but the unset `storageClass` field on the PVC
-  will have the desired effect.
+  In Kubernetes 1.6 the alpha annotation ceases to have meaning, but a default storage class should be
+  configured there to provisions all PVCs, including those with the alpha annotation.