Add Ironic Section in Administrator Guide

Since Ironic is an integration project now. We should add one section
about it in Admin guide.
This commit is part of the bugfix since adding the whole section is
huge. This one is to create a new file for ironic section and add
basic outline.

Change-Id: I355245629ec46be4a44aef6dea33c60306edbb6d
Partial-Bug: #1495898

doc/admin-guide-cloud/source/baremetal.rst

@@ -0,0 +1,49 @@
+.. _baremetal:
+
+.. highlight: ini
+   :linenothreshold:
+
+==========
+Bare Metal
+==========
+
+The Bare Metal service provides physical hardware management features.
+
+Introduction
+~~~~~~~~~~~~
+
+The Bare Metal service provides physical hardware as opposed to
+virtual machines and provides several reference drivers which
+leverage common technologies like PXE and IPMI, to cover a wide range
+of hardware. The pluggable driver architecture also allows
+vendor-specific drivers to be added for improved performance or
+functionality not provided by reference drivers. The Bare Metal
+service makes physical servers as easy to provision as virtual
+machines in a cloud, which in turn will open up new avenues for
+enterprises and service providers.
+
+System architecture
+~~~~~~~~~~~~~~~~~~~
+
+The Bare Metal module is composed of the following components:
+
+#. A RESTful API service
+
+#. A conductor service
+
+#. Various drivers that support heterogeneous hardware
+
+#. A message queue
+
+#. A database for storing information about the resources
+
+.. TODO Add the detail about each component.
+
+Bare Metal deployment
+~~~~~~~~~~~~~~~~~~~~~
+
+#. PXE deploy process
+
+#. Agent deploy process
+
+.. TODO Add the detail about the process of Bare Metal deployment.

doc/admin-guide-cloud/source/index.rst

@@ -27,6 +27,7 @@ Contents
    networking.rst
    telemetry.rst
    database.rst
+   baremetal.rst
    orchestration.rst
    cross_project.rst
    common/app_support.rst