Add the missing title of Configuration Guide
Add the missing title of Configuration Guide

There is no title for Configuration Guide now[1], this patch
is to add it.

backport: pike

[1] https://docs.openstack.org/watcher/pike/configuration/

Change-Id: I82d1b14b9a943cc1a2a22187ff30c75680f9f5d6

openstack/watcher,stackforge/watcher,stackforge/watcher,openstack/watcher