PCI passthrough_whitelist configuration option documentation

[Irena Berezovsky]

pci_passthrough_whitelist can be be specified in different ways, but current documentation of pci_passthrough_whitelist in nova.conf captured in OpenStack Configuration Reference guide, defines only limited option.
There is a need to document available options as it is defined in the https://github.com/openstack/nova-specs/blob/master/specs/juno/implemented/pci-passthrough-sriov.rst specification.

[Atsushi SAKAI (sakaia)]

Let me clearify

This issue need to fix nova help messages.
 i.e. From Configuration Reference, it is automatically generated from nova source code.
It seems to be nothing to do for manual side.
or does this issue track nova code changes?

https://github.com/openstack/nova/blob/stable/kilo/nova/pci/whitelist.py#L27

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/243335

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/243335
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=45ad213b470a03f21e069fce24cc50676c432831
Submitter: Jenkins
Branch: master

commit 45ad213b470a03f21e069fce24cc50676c432831
Author: Stephen Finucane <email address hidden>
Date: Mon Nov 9 22:22:13 2015 +0000

    Improve 'pci' conf options documentation

    The 'pci_passthrough_whitelist' conf option can be be specified in
    different ways, but the current documentation, defines only limited
    option. Similarly the 'pci_alias' option is a JSON dictionary, but this
    is not specificed.

    Further document both option per definition from the 'pci-passthrough-sriov'
    spec.

    Change-Id: I7ecc1dbc3ccc60e174c0057412896d3896d2648e
    Closes-bug: 1381017