tvOS 10.2.2 is only available for the fourth-generation Apple TV. Registered developers can download the update by connecting the Apple TV to a computer with a USB-C cable and installing the beta software using iTunes. Once a beta profile is installed, new updates will be received over-the-air.
No major feature changes or bug fixes were discovered in the first four betas of tvOS 10.2.2, so it appears the update focuses on minor under-the-hood improvements and security enhancements.
tvOS 10.2.2 will be one of the last updates to the tvOS 10 operating system as Apple is already working on the next-generation version of tvOS, tvOS 11. tvOS 11 is currently available for developers and public beta testers.