The update follows the previous one distributed from last December that reached fire tv stick (3rd generation) and fire tv stick lite. For the fire tv stick (2nd generation) we will be waiting. amazon defines it as the most relevant update ever released for fire tv devices.
To manually verify the presence of new updates it is sufficient to follow the settings path -> my fire tv -> information -> verification updates. Amazon is working a lot to improve the software of its fire tv also thanks to the conclusion of important partnerships.