The theme is meant to show banners next to the sidebar, using the above-main-container outlet. The Extra-Banners component uses that outlet by default, but the two components for Category and Tag banners are by default rendered below the header. I wouldn’t want to fork these components, just to set a different default outlet… That’s why I put these instructions:
But if that’s easy to miss, maybe there’s a better way to put it? 
Yeah, that’s easy enough and seems a good approach for this theme. I just added a commit!