I just put up the basic setup for the Challenge Road page, but there's obviously more to add to it over time. Since the Challenge Road is supposed to be a daily / weekly / whatever occurrence, I wanted to let people know that this page exists so that they may add more Challenge Roads to the list when they are introduced. Anyone is free to do so!
In terms of the format, it's simple: the name of the level and part or all of the description, depending on how long it is. If it's too long, just take the first or second paragraphs. Also, make sure to link the level's name to the Steam Workshop page. If you're confused, the first one is up on the page as an example.