Mention Ceph RBD deprection in the user doc to notify the users.

The Ceph RBD intree storage driver is getting deprecated in kubernetes
release 1.28 and users have to be notified about the same.

Author: humblec

Diff for: volumes/rbd/README.md

@@ -1,5 +1,11 @@
 # How to Use it?
 
+NOTE: Ceph RBD in-tree storage driver ( `kubernetes.io/rbd`) has been
+deprecated in kubernetes 1.28 release and will be in removed in subsequent
+releases. The CSI driver for Ceph RBD (https://github.com/ceph/ceph-csi)
+is available for long time now which can be an alternative option for the
+users want to use Ceph RBD volumes in their clusters.
+
 Install Ceph on the Kubernetes host. For example, on Fedora 21
 
     # yum -y install ceph-common