effective_go.html: add a section on type assertions The information was missing, oddly enough.
effective_go.html: add a section on type assertions
The information was missing, oddly enough.

R=golang-dev, rsc, iant
CC=golang-dev
https://codereview.appspot.com/7636044
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go