There are two types of useful documentation: Documentation that builds a mental model for a user, and documentation that answers questions that cannot be answer

There are two types of useful documentation: Documentation that builds a mental model for a user, and documentation that answers questions that cannot be answered from the mental model. The first is done through tutorials and quickstarts, and the second through API references. There's a third type of documentation: Documentation that describes behavior that is contrary to the mental model. This documentation is useless to a user, as there is no reason to seek it out. The benefit to a developer is that they can document bugs instead of fixing them, and blame the users for it.