[Unity] Update doc for revert to snap support

Change-Id: I0114bfd3e050a7dd1110fba88075f22596cd571d

doc/source/admin/emc_unity_driver.rst

@@ -59,6 +59,7 @@ Storage Systems.
 * Modify the user access privilege of a CIFS share.
 * Take/Delete snapshot of a share.
 * Create a new share from snapshot.
+* Revert a share to a snapshot.
 
 
 Supported Network Topologies
@@ -251,6 +252,7 @@ Following driver features are implemented in the plugin.
 * setup_server: Set up and configures share server with given network
   parameters.
 * teardown_server: Tear down the share server.
+* revert_to_snapshot: Revert a share to a snapshot.
 
 
 The :mod:`manila.share.drivers.dell_emc.driver` Module

doc/source/configuration/shared-file-systems/drivers/dell-emc-unity-driver.rst

@@ -56,6 +56,8 @@ The following operations are supported:
 
 -  Shrink a share.
 
+-  Revert a share to a snapshot.
+
 
 Supported network types
 ~~~~~~~~~~~~~~~~~~~~~~~