doc: simplify How to write Go code article
doc: simplify How to write Go code article

This version just tells you what to do, rather
than trying to teach you how it all works.
Should be much better for newcomers.

R=dave, gary.burd, alcosholik, r
CC=golang-dev
https://codereview.appspot.com/8247044

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