doc/go1.4.html: fix typo
doc/go1.4.html: fix typo

LGTM=adg
R=r, adg
CC=golang-codereviews
https://codereview.appspot.com/165890043

tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go