Add description in ProphetStor cinder volume driver

Add this to the description for ProphetStor FC and iSCSI drivers:
ProphetStor Fibre Channel and iSCSI drivers add support for ProphetStor
Flexvisor through OpenStack Cinder. ProphetStor Flexvisor enables commodity
x86 hardware as software-defined storage leveraging well-proven ZFS for
disk management to provide enterprise grade storage services such as snapshots,
data protection with different RAID levels, replication, and deduplication etc.

renew again.

Change-Id: I69e83df508ce42b0d937865cad6211acaca5342f
Closes-Bug: 1369415
Merge "Add description in ProphetStor cinder volume driver"