This also includes some other minor updates to the documentation.

Change-Id: Iafab353727d7622d125b97fbdeaa81525b7a92aa
Reviewed-on: https://go-review.googlesource.com/11123Reviewed-by: Yves Junqueira <yves.junqueira@gmail.com>
Reviewed-by: Russ Cox <rsc@golang.org>