There were some missing bits in the other rst files and Makefile.am(s)
that didn't reflect the rename of the main document. Also add
ddns-confgen.8 manpage.
The ARM and the manpages have been converted into Sphinx documentation
format.
Sphinx uses reStructuredText as its markup language, and many of its
strengths come from the power and straightforwardness of
reStructuredText and its parsing and translating suite, the Docutils.
