The owners of Moto G3 (Moto G 3rd Generation) have reported that they have finally received a notification for upgrading the Android to Android 6.0 Marshmallow. Motorola announced that they will be rolling out the OTA update for Android Marshmallow for all their 2nd generation and above devices. The Marshmallow update for Moto G3 is around 2GB in size. Android 6.0 update bring you all the new features of Marshmallow and will also fix most of the bugs and will remove applications such as Moto Assist and Moto Migrate.
To update your Device, Go to Settings > About phone> System Updates.
Make sure you’re connected to the Internet (preferably Wi-Fi) as the download size of the update is very big. However, Motorola has not yet rolled out the Marshmallow update for Moto G (2nd Gen).