doc: add VolumeGroupSnapshot examples for RBD

examples/rbd/groupsnapshot.yaml

@@ -0,0 +1,13 @@
+---
+apiVersion: groupsnapshot.storage.k8s.io/v1alpha1
+kind: VolumeGroupSnapshot
+metadata:
+  name: rbd-groupsnapshot
+spec:
+  source:
+    selector:
+      matchLabels:
+        # The PVCs will need to have this label for it to be
+        # included in the VolumeGroupSnapshot
+        group: test
+  volumeGroupSnapshotClassName: csi-rbdplugin-groupsnapclass

examples/rbd/groupsnapshotclass.yaml

@@ -0,0 +1,19 @@
+---
+apiVersion: groupsnapshot.storage.k8s.io/v1alpha1
+kind: VolumeGroupSnapshotClass
+metadata:
+  name: csi-rbdplugin-groupsnapclass
+driver: rbd.csi.ceph.com
+parameters:
+  # String representing a Ceph cluster to provision storage from.
+  # Should be unique across all Ceph clusters in use for provisioning,
+  # cannot be greater than 36 bytes in length, and should remain immutable for
+  # the lifetime of the StorageClass in use
+  clusterID: <cluster-id>
+
+  # eg: pool: rbdpool
+  pool: <rbd-pool-name>
+
+  csi.storage.k8s.io/group-snapshotter-secret-name: csi-rbd-secret
+  csi.storage.k8s.io/group-snapshotter-secret-namespace: default
+deletionPolicy: Delete

examples/rbd/pvc.yaml

@@ -3,6 +3,8 @@ apiVersion: v1
 kind: PersistentVolumeClaim
 metadata:
   name: rbd-pvc
+  labels:
+    group: test
 spec:
   accessModes:
     - ReadWriteOnce