tvOS 9.0.1, build number 13T402, is the first firmware update to hit Apple's all-new fourth generation Apple TV, and is considered a minor one since no release notes has been released, suggesting that this update will most likely will be focusing on bug fixes and performance enhancements.
tvOS 9.0.1 is now available to download by simply heading to the Settings app on the Apple TV, and the Software Update. However, this update does not support 3rd- Gen and earlier Apple TVs.