Fixes for the links at the bottom of all HTML manual pages.
This is for the automatically generated documentation at http://www.nmr-relax.com/manual/index.html,
created using latex2html. The links all require double quotes, and some a trailing '/'. The links
fixed are http://www.nmr-relax.com, http://www.nmr-relax.com/manual/ and
http://download.gna.org/relax/manual/relax.pdf.
