Update the N Preview docs now that Studio 2.1 is stable. bug: 28342771 am: 96e6abb am: 39a59d0
am: 86c6f97

* commit '86c6f97bce6beb84e826af02e26e4fd256b385f8':
  Update the N Preview docs now that Studio 2.1 is stable. bug: 28342771

Change-Id: I9d1d81f463768db9f841fe639229702fbca807e6