Steps to reproduce

Run asdf. In help output a line is printed for the asdf env command:

asdf env <command> [executable]      Prints or runs an executable under a command environment

I would assume <command> is an arbitrary command. But from what I can tell needs to be a plugin name or a shim name? I'm also not sure how this differs from executing the shim directly.

FY

Add -h and -V options

Basic getopts version:

  #-----------------------------------------------------------------------
  #  Handle command line arguments
  #-----------------------------------------------------------------------
  while getopts ":hV" opt
  do
    # shellcheck disable=SC2214
    case "${opt}" in

      h|help      ) _usage;    exit 0 ;;
      V|version   ) _version;