Amazon is rolling out a software update for Kindle Fire. Update is available OTA as well as a manual download from Amazon.com. According to Amazon, this update brings improvements to the operation of your Kindle Fire, detailed changelog has not been provided.
Dubbed as version 6.2, this update will automatically download and install on your device if you are connected to WiFi. You can also manually trigger it by clicking on sync in the quick settings bar else you can download the update file from here and copy it your kindleupdates folder on your Kindle drive.
Then you can tap on the update your Kindle icon in the device menu.
More instructions are available here.
Note: It breaks root privileges; OTA Rootkeeper is not working so you will have to re-root your Kindle.