Add a changelog to see all changes into tagged releases

in addition to release notes, it'll be nice to also see the
changelog that happened between releases.

Change-Id: I4548be22c377ec12f0398a248391384126506715

Author: Steve Martinelli

doc/source/history.rst

@@ -0,0 +1 @@
+.. include:: ../../ChangeLog

doc/source/index.rst

@@ -20,7 +20,6 @@ User Documentation
    interactive
    humaninterfaceguide
    backwards-incompatible
-   releases
    man/openstack
 
 Getting Started
@@ -30,6 +29,15 @@ Getting Started
 * Read the source `on OpenStack's Git server`_
 * Install OpenStackClient from `PyPi`_ or a `tarball`_
 
+Release Notes
+-------------
+
+.. toctree::
+   :maxdepth: 1
+
+   releases
+   history
+
 Developer Documentation
 -----------------------