[Bug web/87050] Bump wwwdocs to html5

[jb at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87050

--- Comment #11 from Janne Blomqvist <jb at gcc dot gnu.org> ---
(In reply to Gerald Pfeifer from comment #10)
> (In reply to Janne Blomqvist from comment #0)
> > So apart from the headers, little work ought to be needed for the
> > conversion itself.
> 
> Well, no. :-}  https://gcc.gnu.org/ml/gcc-patches/2018-09/ speaks a
> different language, and that's just part of it, after all I did the
> last year(s) already.

Indeed, it seems I grossly underestimated the amount of work required. Thanks
for doing it!