doc/articles/race_detector: fix some format.
doc/articles/race_detector: fix some format.

R=golang-dev, bradfitz, minux.ma, adg
CC=golang-dev
https://codereview.appspot.com/7137049

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

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