fix broken links (+ a little more structure), re #3145

git-svn-id: svn://develop.studip.de/studip/trunk@25798 c5b85792-5220-0410-ad23-ed5b6b8ad999
fix broken links, re #3130

git-svn-id: svn://develop.studip.de/studip/trunk@25799 c5b85792-5220-0410-ad23-ed5b6b8ad999