Add short names for Volume Snapshot CRDs

This allows end users to run `kubectl get vs`, for example, instead of
`kubectl get volumesnapshot`. The following short names have been
implemented:

* `VolumeSnapshot` - `vs`
* `VolumeSnapshotContent` - `vsc`, `vscs`
* `VolumeSnapshotClass` - `vsclass`, `vsclasses`

client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml

@@ -14,6 +14,9 @@ spec:
     kind: VolumeSnapshotClass
     listKind: VolumeSnapshotClassList
     plural: volumesnapshotclasses
+    shortNames:
+    - vsclass
+    - vsclasses
     singular: volumesnapshotclass
   scope: Cluster
   versions: