Worth the Candle: The Exclusionary Principle, 9th Edition, also known informally as the Exclusion doc, is a currently-ongoing project with daily updates being published by Alexander Wales on Archive Of Our Own. It originated as a Patreon goal, but is available for free to everyone.
It takes the form of a copy of the in-universe 9th edition of the book The Exclusionary Principle pulled from the Infinite Library, with annotations from various characters (including notes from the DM on adapting them to your own games). Each short chapter covers a single Exclusion Zone. The text is designed to be usable without having read Worth the Candle, with an introduction that summarizes the basics of the setting and those chapters that contain story spoilers being marked.