[wwwdocs] Update C++ status with Belfast motions

[Marek Polacek]

On Mon, Nov 25, 2019 at 09:39:25AM -0500, Jason Merrill wrote:
> On Fri, Nov 22, 2019 at 4:51 PM Marek Polacek <polacek@redhat.com> wrote:
> 
> > Committed to git.  Should s/http/https/ the wg21 links.
> >
> > Jason, do we support P1907R1?
> >
> 
> Pretty close, just need to add a bit more checking.

Thanks, won't bother to change it back to unsupported in the table then.

Marek