Document `Cask::Cmd`.

Library/Homebrew/cask/cmd.rb

Library/Homebrew/cask/cmd/--cache.rb

Library/Homebrew/cask/cmd/abstract_command.rb

Library/Homebrew/cask/cmd/abstract_internal_command.rb

Library/Homebrew/cask/cmd/audit.rb

Library/Homebrew/cask/cmd/cat.rb

Library/Homebrew/cask/cmd/create.rb

Library/Homebrew/cask/cmd/doctor.rb

Library/Homebrew/cask/cmd/edit.rb

Library/Homebrew/cask/cmd/fetch.rb

Library/Homebrew/cask/cmd/help.rb

Library/Homebrew/cask/cmd/home.rb

Library/Homebrew/cask/cmd/info.rb

Library/Homebrew/cask/cmd/install.rb

Library/Homebrew/cask/cmd/internal_help.rb

Library/Homebrew/cask/cmd/internal_stanza.rb

Library/Homebrew/cask/cmd/list.rb

Library/Homebrew/cask/cmd/outdated.rb

Library/Homebrew/cask/cmd/reinstall.rb

Library/Homebrew/cask/cmd/style.rb