There was the quick reference card, the User Manual, and the Strategy Guide, all of which I still have.
The Strategy Guide is ostensibly written by "Old Klavis". The first 3 pages teach how to mix potions, giving full details of all potions up to and including the white ones, but there is no mention of the black potions. There are also maps of Mist and Ironfist, but the teleporters to and from Mist main island to the archipelago north of it are omitted. Also there is no sign of the Shrines, and various other things carry labels that do not correspond with the maps in the final game – for example, Albert Newton's residence is called the "Mayor's House". Dragoons' Caverns are named in the right place in Ironfist, but there is a "Mansion" where Corlagon's Estate was eventually put, the Seer appears as a "Store", and the entrance to Snergle's Caverns is marked only by an unlabelled diagram of another mansion.
Next comes a near-complete rundown of the Temple of Baa which fits pretty well with the version in the game. Following that are walkthroughs of the Silver Helm Outpost, the Shadow Guild Outpost, and Dragoons' Caverns, which again correspond very well with the versions in the game as released.
To my mind, this Guide was written fairly late on in the game's development, and I would infer from it that most if not all the dungeons were designed and coded before it was decided where to put them and the layouts of the different areas were finally settled.