doc: update "How to Write Go Code" to use the go tool
doc: update "How to Write Go Code" to use the go tool

R=golang-dev, r, kevlar, rsc
CC=golang-dev
http://codereview.appspot.com/5534045

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