These files are the data from the .txt files from the d2r casc, as well as a couple of helpful extra files. Additional files that aren't directly based on existing .txt files are:
A tiny style sheet that adds the AvQuest font, and an 'avquest' class that applies the font and a couple additional styles that adjusts the font to look closer to diablo 2. https://blizzhackers.github.io/d2data/css/d2font.css