.hgignore: add comment setting policy
.hgignore: add comment setting policy

R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/44860043

golang/exp,AkihiroSuda/golang-exp-aspectgo,go-src/inotify,AkihiroSuda/golang-exp-aspectgo,JamesDunne/exp,golang/exp,golang/exp,AkihiroSuda/golang-exp-aspectgo,JamesDunne/exp