doc: update go1.2.txt
doc: update go1.2.txt

Will submit once I can fill in the CL XXX number.

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/12912044

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang