Lenovo launched the Vibe K4 Note back in January in India & it was a great device & successful also.
The Lenovo K4 Note smartphone was launched with Android Lollipop as base OS. Now the company has pushed Marshmallow update for the device. The update brings some beauty of Android Marshmallow on board which includes Google Now on Tap, Doze, Battery saver & app permission etc.
The update weights around 1.6GB in size. So you need to be on wifi in order to download this update. The update comes in stages so you need to be patient to get this update to your device. While you can check manually also by going to Settings>About Phone>System Update