Do not include reno releasenotes in normal documentation

Per the recent release note guidelines for libraries [1],
reno based release notes will be moved out from the normal docs.
The previous (partial) release notes are also moved to
releasenotes directory. The developer documentation now
has a link to the releasenote web site.

In addition, having reno directive in normal sphinx document
prevents users from generating our docs from release tarballs.

[1] http://lists.openstack.org/pipermail/openstack-dev/2015-November/080694.html

Change-Id: I817f1a7331b8664486544c82e1a9a917864601bf
Closes-Bug: #1520096

doc/source/index.rst

@@ -30,7 +30,5 @@ lower level programming details or APIs.
 History
 -------
 
-.. toctree::
-   :maxdepth: 1
-
-   history
+Release notes is available at
+http://docs.openstack.org/releasenotes/python-neutronclient/.

releasenotes/source/index.rst

@@ -3,3 +3,11 @@ Release Notes
 =============
 
 .. release-notes::
+
+Past release notes
+------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   old_relnotes

releasenotes/source/old_relnotes.rst

@@ -1,8 +1,6 @@
-=============
-Release Notes
-=============
-
-.. release-notes::
+=================
+Old Release Notes
+=================
 
 2.2.2
 -----