[DOXIA-547] Upgrade to Maven Parent 30

Update site.xml as well due to changes in Maven Site Plugin and Doxia Site Renderer

git-svn-id: https://svn.apache.org/repos/asf/maven/doxia/doxia/trunk@1777810 13f79535-47bb-0310-9956-ffa450edef68
1 file changed