Changed targetSdkVerion from "android-MNC" to "MNC". Also--per
preview/setup-sdk.html -- changed the minSdkVersion to "MNC" in
both places (if people are building apps for the preview release,
the minimum SDK version has to be MNC to keep the app from getting
installed onto devices running production Android).
See first comment for doc stage location.
bug: 21443485
Change-Id: I4cc5f16d53cd795b2db156c99db7c46f14d0ce65
95bdf6111d