doc: fix go_spec spelling error
doc: fix go_spec spelling error

R=rsc, gri
CC=golang-dev
http://codereview.appspot.com/2985041

Committer: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>

h8liu/golang,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,h8liu/golang,apparentlymart/golang,dsriram/golang,ssrl/go,apparentlymart/golang,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,ssrl/go,pombredanne/go-deleteme,gnanderson/go,ssrl/go,tv42/old-go,dsriram/golang,gnanderson/go,apparentlymart/golang,h8liu/golang,apparentlymart/golang,h8liu/golang,dsriram/golang,dsriram/golang,tv42/old-go,apparentlymart/golang,tv42/old-go,ssrl/go,h8liu/golang,pombredanne/go-deleteme,gnanderson/go,h8liu/golang,ssrl/go,ssrl/go,dsriram/golang,h8liu/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,gnanderson/go,pombredanne/go-deleteme,apparentlymart/golang,ssrl/go,pombredanne/go-deleteme,gnanderson/go,dsriram/golang,gnanderson/go