[tex-live] Broken link in texlive-en.html

[Karl Berry]

    In texlive-en.html the link texmf-dist/doc/fonts/free-math-font-survey
    (section 2.6) is broken in TL pretest. The directory does not exist.

Thanks Uwe.  I had to remove the survey from TL some year(s) ago since
Stephen Hartke unfortunately stopped answering my mail and never managed
to re-upload his document with a license.

So I removed the reference to it, which left nothing but a reference to
tug.org/fonts, which hardly seemed worth a whole (sub)section, so I
deleted it and altered the one reference to it.

Thanks,
Karl