http://www.pcgamer.com/dawn-of-war-3-adds-modding-tools-and-steam-workshop-support/

Back in June, Dawn of War 3's Annihilation update introduced new multiplayer modes, maps, and doctrines—such was the community's most sought after features at the time. 

Now, its latest comprehensive update adds modding tools with Steam Workshop support, balance improvements, and a number of quality of life adjustments as Relic continues its drive for player feedback.