Note that it says in the tutorial:
"In this example, we'll decode three insula-based coactivation networks drawn from Chang, Yarkoni, Khaw, & Sanfey (2012). You should substitute your own images into the list below. "
If you want those images, I think they are hosted on NeuroVault:
Just a guess, but I'd say this one is pIns, vIns, and dIns, respectively. Are you familar with Github? If you are concerned about this in the tutorial, you could add a note and link to the reader to find (and download) the data from NeuroVault, but doing that would be dependent on them reading it! Ha.