Add 'help' command for printing USAGE
Add 'help' command for printing USAGE

Also added mention of which actions don't take a list of modules.

tadzik/panda,hoelzro/panda,sjn/panda,timo/panda,sjn/panda,sjn/panda,nbrown/panda,tadzik/panda,stmuk/panda,nbrown/panda,tadzik/panda,jonathanstowe/panda,hoelzro/panda,timo/panda,hoelzro/panda,jonathanstowe/panda,stmuk/panda