The following documentation resources are available:
User documentation
The user documentation is bundled with Mushroom. It is available as a PDF document along the application on the disk image.
Project Builder/Xcode compatibility
Mushroom is able to read the versions 38 and 39 of Project Builder and Xcode's project files. Those versions respectively correspond to Jaguar's Developer Tools and Xcode. The older projects have to be converted with Project Builder or Xcode before Mushroom can read them.