These are old. Don't use them!
Place all files in Documents/My Games/particlefleet/prpldocs (or your OS appropriate particlefleet/prpldocs directory).
prpldocindex.txt contains the list of files (sections in the resulting documentation). Press “shift-d” when on the main menu of the game to compile the docs. PRPLDocs.html will be created in the prpldocs directory after the compile (which happens instantly).