It means posting things that target angry people so that they will click and view your post. The post achieves this aim by saying or showing things that make the people even more angry. It's hard to think of an example without violating the italki rules, but I'll try. Suppose there are people who are upset about the fact that the city streets are not clean. Someone could post pictures of people throwing litter on the street. People who are upset would click on that. That's "rage baiting".