Weighing in at around 1,112MB, the update includes all the usual Marshmallow goodies such as Doze, Google Now on Tap, and redesigned app permissions, as well as some other changes including those related to fingerprints.
As is usually the case with OTA roll outs, it might take some time before the update notification pops up on your device. Meanwhile, if you feel impatient, you can manually check for the update by heading to your device's Settings menu.
Thanks for the tip Shubham Sharma!!!