OADP-5246: Slight update to OADP / ROSA documentation

Signed-off-by: A.Arnold <anarnold@redhat.com>

Author: anarnold97

modules/installing-oadp-rosa-sts.adoc

@@ -11,7 +11,17 @@ AWS Security Token Service (AWS STS) is a global web service that provides short
 
 [IMPORTANT]
 ====
-Restic and Kopia are not supported in the OADP on ROSA with {aws-short} {sts-short} environment. Verify that the Restic and Kopia node agent is disabled.
+Restic is unsupported.
+
+Kopia file system backup (FSB) is supported when backing up file systems that do not have Container Storage Interface (CSI) snapshotting support.
+
+Example file systems include the following:
+
+* Amazon Elastic File System (EFS)
+* Network File System (NFS)
+* `emptyDir` volumes
+* Local volumes
+
 For backing up volumes, OADP on ROSA with {aws-short} {sts-short} supports only native snapshots and Container Storage Interface (CSI) snapshots.
 
 In an Amazon ROSA cluster that uses STS authentication, restoring backed-up data in a different {aws-short} region is not supported.