Yu Televentures have now started rolling out the all new Android 5.0 Lollipop based Cyanogen OS 12 OS for its Yureka smartphone. The update is now rolling out over-the-air (OTA), so you will receive the notification to install the update in the coming days. But if you want then you can manually check for update by going to Settings > About Phone > Software update.
There is no official change-log, but you can expect to see all the Lollipop features like Material UI, enhanced notifications, and many more.