The news was first revealed by Josh Holmes, the studio manager at Microsoft's 343 Industries, which is currently in the middle of developing Halo 5. In response to a fan question about a possible limited edition Xbox One console for the game, Holmes wrote, "There is a limited edition console coming, yes. It hasn't been revealed yet, but it's pretty sweet. :)."
While there are indeed no details about what the limited edition Xbox One will be like, it's highly likely that it will contain a copy of Halo 5 bundled with the console, that it and the controller will have an art style similar to what is seen in the game itself. We may get more information during E3 2015 this June. Halo 5: Guardians itself is currently scheduled to launch on October 27.
Source: Josh Holmes (Twitter)