Update the N Preview docs now that Studio 2.1 is stable. bug: 28342771 am: 96e6abb am: 39a59d0 am: 86c6f97
am: c7984b5

* commit 'c7984b5d62b511a17f3030641d44efc2b147a776':
  Update the N Preview docs now that Studio 2.1 is stable. bug: 28342771

Change-Id: I01396349b0ec8e88be46888f8a44f8f93c4c0f8d