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

LGTM=bradfitz
R=golang-codereviews, gobot, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/81890044

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