Update README for 2.x.
Update README for 2.x.

nitrogen/nitrogen,nitrogen/nitrogen,choptastic/nitrogen,joaohf/nitrogen,kevinmontuori/nitrogen,kevinmontuori/nitrogen,choptastic/nitrogen,choptastic/nitrogen,kevinmontuori/nitrogen,stuart-thackray/nitrogen,stuart-thackray/nitrogen,stuart-thackray/nitrogen,joaohf/nitrogen,nitrogen/nitrogen,joaohf/nitrogen