hnas_iscsi is deprecated by Cinder in Ocata release

[Chason Chan]

This bug tracker is for errors with the documentation, use the following as a template and remove or add fields as you see fit. Convert [ ] into [x] to check boxes:

- [x] This doc is inaccurate in this way: hnas_iscsi is deprecated by Cinder in Ocata release.
- [ ] This is a doc addition request.
- [x] I have a fix to the document that I can paste below including example: input and output.

We should remove ``hnas_iscsi`` from supported storage backends list.

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-----------------------------------
Release: 8.1.0.dev160 on 2018-12-10 17:08:58
SHA: cb0cb441c2c39cd126ea0662e91b241de25c1b3f
Source: https://opendev.org/openstack/kolla-ansible/src/doc/source/reference/storage/cinder-guide.rst
URL: https://docs.openstack.org/kolla-ansible/latest/reference/storage/cinder-guide.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/665325

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/665325
Committed: https://git.openstack.org/cgit/openstack/kolla-ansible/commit/?id=b7ca065edf11d0c4ee8e911c7316cec87bd10d08
Submitter: Zuul
Branch: master

commit b7ca065edf11d0c4ee8e911c7316cec87bd10d08
Author: chenxing <email address hidden>
Date: Fri Jun 14 04:02:07 2019 -0400

    Remove ``hnas_iscsi`` from the supported storage backends list of Cinder

    The Hitachi NAS Platform iSCSI driver was marked as not supported by
    Cinder in the Ocata realease[1].

    [1] https://review.opendev.org/#/c/444287/

    Change-Id: I1a25789374fddaefc57bc59badec06f91ee6a52a
    Closes-Bug: #1832821

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/kolla-ansible 9.0.0.0rc1 release candidate.