GitHub Backup

Noticed this from the minutes (sorry I wasn't there today):

| <fjh> we should explore automating pull of github for w3c archive as
backup mechanism

If people feel it's necessary or it's mandated by some process, we can ask
around with the ASF infra team because I know they've got lots of tooling
set up for GitHub mirrors.

But also note that _everyone_ who clones the repo has an archive of the
repo. That's DVCS :-D. So, while I think it's a valuable thing for
long-term preservation, in the short term it's probably completely
unnecessary from a disaster-recovery standpoint as long as any of us are
actively involved in the project.