docs: add docs for volumegroupreplication CR

add docs for volumegroupreplication and volumegroupreplicationclass
CRs.

Signed-off-by: Nikhil-Ladha <nikhilladha1999@gmail.com>

docs/volumegroupreplication.md

@@ -0,0 +1,38 @@
+# VolumeGroupReplication
+
+VolumeGroupReplication is a namespaced resource that contains references to storage object to be grouped and replicated, VolumeGroupReplicationClass corresponding to the driver providing replication, VolumeGroupContent and VolumeReplication CRs.
+
+`volumeGroupReplicationClassName` is the name of the class providing group replication.
+
+`volumeReplicationClassName` is the name of the class providing the replication for volumeReplication CR.
+
+`volumeReplicationName` is the name of the volumeReplication CR created by this volumeGroupReplication CR
+
+`volumeGroupReplicationContentName` is the name of the volumeGroupReplicationConten CR created by this volumeGroupReplication CR.
+
+`replicationState` is the state of the volume being referenced. Possible values are `primary`, `secondary` and `resync`.
+
++ `primary` denotes that the volume is primary
++ `secondary` denotes that the volume is secondary
++ `resync` denotes that the volume needs to be resynced
+
+`source` contains the source of the volumeGroupReplication i.e, the selectors to match the PVC/PVs to be replicated.
+
++ `selector` is a label selector to filter the pvcs that are to be included in the group replication
+
+
+``` yaml
+apiVersion: replication.storage.openshift.io/v1alpha1
+kind: VolumeGroupReplication
+metadata:
+  name: volumegroupreplication-sample
+  namespace: default
+spec:
+  volumeReplicationClassName: volumereplicationclass-sample
+  volumeGroupReplicationClassName: volumegroupreplicationclass-sample
+  replicationState: primary
+  source:
+    selector:
+      matchLabels:
+        group: replication
+```

docs/volumegroupreplicationclass.md

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+# VolumeGroupReplicationClass
+
+`VolumeGroupReplicationClass` is a cluster scoped resource that contains driver related configuration parameters for volume group replication.
+
+`provisioner` is name of the storage provisioner.
+
+`parameters` contains key-value pairs that are passed down to the driver. Users can add their own key-value pairs. Keys with `replication.storage.openshift.io/` prefix are reserved by operator and not passed down to the driver.
+
+## Reserved parameter keys
+
++ `replication.storage.openshift.io/group-replication-secret-name`
++ `replication.storage.openshift.io/group-replication-secret-namespace`
+
+``` yaml
+apiVersion: replication.storage.openshift.io/v1alpha1
+kind: VolumeGroupReplicationClass
+metadata:
+  name: volumegroupreplicationclass-sample
+spec:
+  provisioner: example.provisioner.io
+  parameters:
+    replication.storage.openshift.io/group-replication-secret-name: secret-name
+    replication.storage.openshift.io/group-replication-secret-namespace: secret-namespace
+```