doc/install: document system requirements for the FreeBSD/ARM port
doc/install: document system requirements for the FreeBSD/ARM port

R=golang-dev, r, mikioh.mikioh
CC=golang-dev
http://codereview.appspot.com/6816080

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go