Adds build job for block storage admin manual

Change-Id: I42c845db327db435acd005c25c32ff39637396d0
Reviewed-on: https://review.openstack.org/25384
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Khai Do <zaro0508@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins