Update glusterfs README about uninstall playbook

Signed-off-by: Saravanakumar Arumugam <sarumuga@redhat.com>

playbooks/openshift-glusterfs/README.md

@@ -99,3 +99,12 @@ See the documentation in the role's directory for further details.
 The `openshift_hosted` role recognizes `glusterfs` as a possible storage
 backend for a hosted docker registry. It will also, if configured, handle the
 swap of an existing registry's backend storage to a GlusterFS volume.
+
+## Playbook: uninstall.yml
+
+This playbook is intended to uninstall all GlusterFS related resources
+on an existing OpenShift cluster.
+It has all the same requirements and behaviors as `config.yml`.
+
+If the variable `openshift_storage_glusterfs_wipe` is set as True,
+it clears the backend data as well.