No.
So far with 3 books published, no side-story material from the comic has been included, and no original side-stories were created. Only the main plot is focused on. This doesn't rule out such diversions in the future, however, the authors use the comic as the primary story telling medium, so when they feel the urge to divert it will typically be there.
There are prologues that could be considered brand new sections, but they are directly related to the plot, so I doubt they fall under what you're asking.