Restructured the doc of kolla-ansible

Created the admin directory, remove some files from
user dir and placed into admin and contributor.

For more detail, see the doc migration spec.
http://specs.openstack.org/openstack/docs-specs/specs/pike/os-manuals-migration.html

Change-Id: I84c565d7d14a4d90270a53e14ab93a10f7ffb9b7
Partially-Implements: blueprint ka-queens-doc-restructure

doc/source/admin/index.rst

+Admin Guides
+============
+
+.. toctree::
+   :maxdepth: 1
+
+   advanced-configuration
+   production-architecture-guide
+   deployment-philosophy

doc/source/contributor/index.rst

@@ -5,6 +5,7 @@ Developer Docs
    :maxdepth: 1
 
    CONTRIBUTING
+   kolla-for-openstack-development
    vagrant-dev-env
    running-tests
    bug-triage

doc/source/index.rst

@@ -33,6 +33,13 @@ For information on building container images for use with Kolla-Ansible, please
 refer to the `Kolla image documentation
 <https://docs.openstack.org/kolla/latest/>`_.
 
+Admin Guides
+============
+
+.. toctree::
+   :maxdepth: 2
+
+   admin/index
 
 User Guides
 ===========

doc/source/user/index.rst

@@ -4,13 +4,9 @@ User Guides
 .. toctree::
    :maxdepth: 1
 
-   deployment-philosophy
-   production-architecture-guide
    quickstart
    multinode
    multi-regions
-   advanced-configuration
    operating-kolla
    security
-   kolla-for-openstack-development
    troubleshooting