doc/reference.html: update list of sub-repositories.
doc/reference.html: update list of sub-repositories.

R=golang-dev, bradfitz, r
CC=golang-dev
https://codereview.appspot.com/8766043

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