doc: remove reference to bug count from install.html
doc: remove reference to bug count from install.html

Fixes issue 1574.

R=rsc, r2
CC=golang-dev
http://codereview.appspot.com/4240066
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go