docs: Fix volume encryption link
Currently, the volume encryption documentation has a link that
points to itself, instead of pointing to the Horizon docs.
This patch updates the link to point to the Horizon docs.
@@ -109,7 +109,7 @@ the volume.
The OpenStack dashboard (horizon) supports creating the encrypted
volume type as of the Kilo release. For instructions, see
`Create an encrypted volume type
-<https://docs.openstack.org/cinder/latest/configuration/block-storage/volume-encryption.html#create-an-encrypted-volume-type>`_.
+<https://docs.openstack.org/horizon/latest/admin/manage-volumes.html#create-an-encrypted-volume-type>`_.
Create an encrypted volume
~~~~~~~~~~~~~~~~~~~~~~~~~~
