[patch] update db2 role storage class doc for ref to db2 doc (#1279)

Co-authored-by: Matthieu Leroux <matthieulrx@nl.ibm.com>
Co-authored-by: Andrew Whitfield <whitfiea@uk.ibm.com>

ibm/mas_devops/roles/db2/README.md

@@ -136,6 +136,8 @@ Determines if the role should rotate the LDAP password for current LDAP user con
 
 Role Variables - Storage
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+We recommend reviewing the Db2 documentation about the certified storage options for Db2 on Red Hat OpenShift. Please ensure your storage class meets the specified deployment requirements for Db2. [https://www.ibm.com/docs/en/db2/11.5?topic=storage-certified-options](https://www.ibm.com/docs/en/db2/11.5?topic=storage-certified-options)
+
 ### db2_meta_storage_class
 Storage class used for metadata. This must support ReadWriteMany