exp/cookiejar: update PublicSuffixList doc comment to match the
examples at http://publicsuffix.org/.

That website previously listed pvt.k12.wy.us, but that was an error,
as confirmed by correspondance with submissions@publicsuffix.org, and
the website was fixed on 2013-01-23.

R=adg
CC=dr.volker.dobler, golang-dev
https://codereview.appspot.com/7241053