net/http: remove an errant space
net/http: remove an errant space

Made the godoc overview section oddly indented
compared to the other code blocks.

R=golang-dev, mikioh.mikioh, dsymonds, r
CC=golang-dev
http://codereview.appspot.com/5645060

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go