Well, press the red button while the Amiga is running, then press the Help key. Press Esc to interrupt output.
A hardcopy of the help listing was the only manual IIRC.
The main impact of the AR1 was that it could not write to usual AmigaDOS disks. You had to format disks in a special way and then there was an Amiga utility to copy files from AR-DOS disks to AmigaDOS disks.
Bye,
Thomas