Just looked at the release notes linked in the link from the first post, passed them through a machine translator, and was disappointed at how useless they are.
EDIT: 2024
Updated 9 October 2024
Amazon regularly changes the internal software of its devices to improve your experience. The operating system of your Kindle e-reader and other pre-installed software automatically receive updates via the Internet. We would like to inform you that a new update will be available for your Kindle e-reader. It will improve its security and performance, add patches and offer new features. In this update, the software version of the Kindle 5.16.21 e-reader is updated to 5.17.1 or later.
This update weighs 370 MB.
This notification will also be available at
www.amazon.fr/help/sw/kindle.
By thanking you for your interest in Amazon devices and services,
The Amazon Appliances team