doc/articles/laws_of_reflection.html: fix name of variable
Thanks to c.emil.hessman@gmail.com for pointing out the error.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12572043
all: fix up language in a couple of comments
Leftovers from 11699043

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12558046