Add networking bugtracker to main demo page

[benjamincburns]

Should help to direct people to the websockproxy issue tracker when reporting network problems.

[benjamincburns]

@s-macke I'm not sure if you want to review changes like this prior to merge. Since this one is pretty benign, I suppose I'll merge it now and follow whatever git workflow you use for the gh-pages branch (either cherry-picking, ff-merge, etc).

Please do come and yell at me if you'd prefer that I didn't do this sort of thing :-)