Adds GitHub ribbon

git-svn-id: https://svn.apache.org/repos/asf/struts/site@1566158 13f79535-47bb-0310-9956-ffa450edef68
Updates generated content

git-svn-id: https://svn.apache.org/repos/asf/struts/site@1566159 13f79535-47bb-0310-9956-ffa450edef68