Updates an important message regarding block devices and filesystem PVCs

Author: Steven Smith

modules/installation-registry-storage-block-recreate-rollout-bare-metal.adoc

@@ -14,10 +14,12 @@ To allow the image registry to use block storage types during upgrades as a clus
 
 [IMPORTANT]
 ====
-Block storage volumes are supported but not recommended for use with the image
+Block storage volumes, or block persistent volumes, are supported but not recommended for use with the image
 registry on production clusters. An installation where the registry is
 configured on block storage is not highly available because the registry cannot
 have more than one replica.
+
+If you choose to use a block storage volume with the image registry, you must use a filesystem Persistent Volume Claim (PVC).
 ====
 
 .Procedure