I think that all mods should contain it's own documentation inside the mod. Like html files and pictures.
Then add a feature in the game which allows the player to view a list of all the mods installed which allows the player to select a mod and open it's documentation inside the game. That way, instead of having to check a server's website or forum page and then look up all the mods it uses, the player can find all the information they need in one location all while playing the game and not having to open a browser and switch back and forth from the game and the browser.