exp/norm: correct package doc comment
exp/norm: correct package doc comment

Fixes issue 2118.

R=golang-dev, r, iant
CC=golang-dev
http://codereview.appspot.com/4815073
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go