Add check to verify that doc/index.textile announces the latest release

git-svn-id: https://svn.apache.org/repos/asf/buildr/trunk@1448396 13f79535-47bb-0310-9956-ffa450edef68
Cleanup the header in the highlights section

git-svn-id: https://svn.apache.org/repos/asf/buildr/trunk@1448397 13f79535-47bb-0310-9956-ffa450edef68