Don't build releasenotes in normal docs build
Don't build releasenotes in normal docs build

The release notes system exists in parallel and publishes to
http://docs.openstack.org/releasenotes/os-client-config/. When we build
them in the normal doc build, it causes problems for distro packagers.

Change-Id: I6b084a1ad6836beac991d03c5f134203512150ac

stackforge/python-openstacksdk,dtroyer/python-openstacksdk,dtroyer/os-client-config,openstack/os-client-config,openstack/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk,stackforge/python-openstacksdk