Use the image in the instructions - it gives you all except for the launchfiles you should launch on your Linux PC to make the Brick load the controller!
Instructions to get a working image for your SD Card can be found here:
If you want, here is a HowTo using Docker Containers created by Mikael Valot.
This repository contains the node for the Lego EV3 for ROS.
Early Demonstration (Recored some time ago): Driving with ROS Controller Diff Drive