Rising Storm GOTY or non-GOTY

I'm pretty sure that GOTY was just an update that all owners of Rising Storm received for free, so essentially there are no non-GOTY copies, but the only proof I could dig up was from a PC Gamer article briefly mentioning this fact at the end. I tried digging through Steam News and Tripwire official page but could not find anything to confirm this. Could someone help me out with a more official statement confirming this?

Thanks a lot!