As part of Google, Motorola garnished a reputation for speedy updates. These days the company has a new owner, and those OTAs don't seem to come out as reliably as they used to. But Motorola hasn't gone back on its promise to bring Marshmallow to something, and now it's beginning its rollout for the 2015 Moto X Style and the 2014 Moto X, according to Senior Director David Schuster.
This is just the initial wave, and for the time being, only people in Brazil and India are getting the Moto X Style update. The 2014 Moto X OTA is even more limited, as it's currently only hitting devices in Brazil.
Other countries should receive the Android 6.0 update in stages over the next few weeks. The changelog is available, so you can peruse that at the link below while you wait.