Update docs to mention IPMI sensors with agent drivers

[Haomeng,Wang]

Two new agent_ipmitool and agent_pyghmi drivers also support sending sensor data to Ceilometer, missing in our doc doc/source/deploy/install-guide.rst 'IPMI support' section.

[Haomeng,Wang (whaom)]

In the previous change[1] , we missed these agent* drivers.

[1] https://review.openstack.org/#q,I5eb72bd26d8ca50ffc5696e378b1c3beaa117fd3,n,z

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/121742
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=97f14be1ab5a06c2eaa3b6dfff6af729ea645d17
Submitter: Jenkins
Branch: master

commit 97f14be1ab5a06c2eaa3b6dfff6af729ea645d17
Author: Haomeng, Wang <email address hidden>
Date: Mon Sep 15 23:33:52 2014 -0400

    Sync the doc with latest code

    Our agent_ipmitool, agent_ilo, iscsi_ilo, pxe_ilo and agent_pyghmi
    drivers also support sending notifications to Ceilometer. However,
    in our install-guide.rst, we just mentioned pxe_ipmitool and
    pxe_ipminative drivers, so the documentation needs to be synced with
    current code.

    Change-Id: Ic6dec44ba11177d0a350c5b4e3cf1eae3658c1b7
    Closes-Bug: #1369838