Update and extend the configuration_file group and enable linking. Commit other cleanups from multi-version Doxygen testing.  Update title that was left behind many years ago.

(issue ASTERISK-20259)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@375182 65c4cc65-6c06-0410-ace0-fbb531ad65f3