api: update next.txt
api: update next.txt

LGTM=rsc
R=golang-codereviews, rsc
CC=adg, golang-codereviews
https://codereview.appspot.com/99530044

apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang