Update document theme and section headers

This commit updates the document theme. It is clear, simple, up-to-date
and beautiful. And this commit also updates section headers to fix the
document index.

Change-Id: Ia1e8e16e5f5ddb06e4c4ccb4979b0750b88a4db4
diff --git a/doc/source/conf.py b/doc/source/conf.py
index cbfcc09..f11d96a 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -27,6 +27,8 @@
 import subprocess
 import warnings
 
+import openstackdocstheme
+
 # Build the plugin registry
 def build_plugin_registry(app):
     root_dir = os.path.dirname(
@@ -117,7 +119,7 @@
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
-html_theme = 'nature'
+html_theme = 'openstackdocs'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
@@ -125,7 +127,7 @@
 #html_theme_options = {}
 
 # Add any paths that contain custom themes here, relative to this directory.
-#html_theme_path = []
+html_theme_path = [openstackdocstheme.get_html_theme_path()]
 
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
diff --git a/doc/source/index.rst b/doc/source/index.rst
index 1264ecc..c4affd2 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -2,18 +2,16 @@
 Tempest Testing Project
 =======================
 
---------
 Overview
---------
+========
 
 .. toctree::
    :maxdepth: 2
 
    overview
 
-------------
 Field Guides
-------------
+============
 Tempest contains tests of many different types, the field guides
 attempt to explain these in a way that makes it easy to understand
 where your test contributions should go.
@@ -26,11 +24,9 @@
    field_guide/scenario
    field_guide/unit_tests
 
-=========
 For users
 =========
 
----------------------------
 Tempest Configuration Guide
 ---------------------------
 
@@ -40,7 +36,6 @@
    configuration
    sampleconf
 
----------------------
 Command Documentation
 ---------------------
 
@@ -53,11 +48,9 @@
    workspace
    run
 
-==============
 For developers
 ==============
 
------------
 Development
 -----------
 
@@ -70,7 +63,6 @@
    test_removal
    write_tests
 
--------
 Plugins
 -------
 
@@ -80,7 +72,6 @@
    plugin
    plugin-registry
 
--------
 Library
 -------
 
@@ -89,7 +80,6 @@
 
    library
 
-==================
 Indices and tables
 ==================
 
diff --git a/releasenotes/source/conf.py b/releasenotes/source/conf.py
index 97e3a4d..d240467 100644
--- a/releasenotes/source/conf.py
+++ b/releasenotes/source/conf.py
@@ -111,7 +111,7 @@
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
-html_theme = 'default'
+html_theme = 'openstackdocs'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
@@ -119,7 +119,9 @@
 # html_theme_options = {}
 
 # Add any paths that contain custom themes here, relative to this directory.
-# html_theme_path = []
+import openstackdocstheme
+
+html_theme_path = [openstackdocstheme.get_html_theme_path()]
 
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
diff --git a/releasenotes/source/index.rst b/releasenotes/source/index.rst
index adec7a7..d2be814 100644
--- a/releasenotes/source/index.rst
+++ b/releasenotes/source/index.rst
@@ -1,5 +1,5 @@
 ===========================
- tempest Release Notes
+ Tempest Release Notes
 ===========================
 
  .. toctree::
diff --git a/test-requirements.txt b/test-requirements.txt
index 13950bd..beb456d 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -10,3 +10,4 @@
 coverage>=4.0 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 flake8-import-order==0.11 # LGPLv3
+openstackdocstheme>=1.5.0 # Apache-2.0