Update volume delete api-ref
This patch update volume delete section in api-ref
to understand preconditions more correctly
Partial-Bug:
@@ -507,9 +507,13 @@ Preconditions
- Volume status must be ``available``, ``in-use``, ``error``,
``error_restoring``, ``error_extending``, ``error_managing``,
- and must not be migrating, attached, belong to a group or have snapshots.
+ and must not be ``migrating``, ``attached``, ``awaiting-transfer``,
+ belong to a group, have snapshots or be disassociated from
+ snapshots after volume transfer.
-- You cannot already have a snapshot of the volume.
+- The ``cascade`` option can be passed in the request if you want
+ all snapshots of this volume to be deleted automatically,
+ which should allow the volume deletion to succeed.
- You cannot delete a volume that is in a migration.
