Mention GlusterFS deprecation in the examples guide.

Considering GlusterFS in-tree storage driver has been deprecated
in 1.25 and then removed in 1.26, it has to be notified to the users
who are referring the example yamls here. Eventually we will remove
the example yamls while these kubernetes versions go unsupported.

Signed-off-by: Humble Chirammal <humble.devassy@gmail.com>

volumes/glusterfs/README.md

@@ -1,5 +1,10 @@
 ## GlusterFS
 
+
+NOTE: GlusterFS in-tree storage driver ( `kubernetes.io/glusterfs`) which was
+deprecated in kubernetes 1.25 release is removed entirely  in `v1.26`. Volumes
+must be migrated to an alternate storage solution before upgrading to `v1.26`.
+
 [GlusterFS](http://www.gluster.org) is an open source scale-out filesystem.
 These examples provide information about how to allow containers use GlusterFS
 volumes.