.update-copyright.conf: Configure update-copyright

I haven't configured the copyright blurbs, because we don't have to
use that functionality if we're just maintaining an AUTHORS file.

We're taking advantage of the automatic name detection that landed in
update-copyright 0.6.2 [1], so downstream lesson maintainers won't
have to tweak .update-copyright.conf (assuming they name their local
repository directory appropriately).

[1]: http://git.tremily.us/?p=update-copyright.git;a=commit;h=87352a043d30d2812c0db3d65676b9766957773b