Make --use-label-envar more visible.  Name the correct envar.
@@ -219,7 +219,7 @@ def add_arguments_extended(parser: KGTKArgumentParser, parsed_shared_args: Names
type=optional_bool, nargs='?', const=True, default=False)
parser.add_argument( "--use-label-envar", dest="use_label_envar",
- help=h("If true, use the KGTK_LABEL envar for the label file if no --label-file. (default=%(default)s)."),
+ help="If true, use the KGTK_LABEL_FILE envar for the label file if no --label-file. (default=%(default)s).",
metavar="True/False",
type=optional_bool, nargs='?', const=True, default=use_label_envar_default)
