- new developer/index.xml

- add references from the subdocuments to the index file (<parentdocument>)
- fix German sitemap reference revision # to be up-to-date


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99247 13f79535-47bb-0310-9956-ffa450edef68