Added OSDOCS-140 to 4.0 files

Author: mburke5678

modules/efk-logging-elasticsearch-persistent-storage.adoc

@@ -48,6 +48,15 @@ openshift_logging_es_pvc_size=104802308Ki
 openshift_logging_es_pvc_prefix=es-logging
 ----
 
+If using dynamically provisioned PVs, the {product-title} logging installer creates PVCs 
+that use the default storage class or the PVC specified with the `openshift_logging_elasticsearch_pvc_storage_class_name` parameter.
+
+If using NFS storage, the {product-title} installer creates the persistent volumes, based on the `openshift_logging_storage_*` parameters 
+and the {product-title} logging installer creates PVCs, using the `openshift_logging_es_pvc_` paramters.
+Make sure you specify the correct parameters in order to use persistent volumes with EFK.
+Also set the `openshift_enable_unsupported_configurations=true` parameter in the Ansible inventory file, 
+as the logging installer blocks the installation of NFS with core infrastructure by default.
+
 [WARNING]
 ====
 Using NFS storage as a volume or a persistent volume (or via NAS such as