Motorola has posted the detailed release notes of the Android 5.1 update for the 1st gen and 2nd gen Moto X along with the Moto E on its website today indicating the imminent rollout of the update. Motorola has posted the changelog for the AT&T as well as the Pure edition 2nd gen Moto X suggesting that the update for both handsets will go out live at nearly the same time. The full release notes of the Android 5.1 update for the 2nd gen Moto X is below. The Lollipop release notes for the 1st gen Moto X can be found here. Motorola had announced in early April that the 1st gen Moto X, Moto E and Moto G LTE will be directly updated to Android 5.1 Lollipop thereby completely skipping the Android 5.0 update.
