parse-options: clarify PARSE_OPT_NOARG description

Here "takes no argument" means "does not take an argument".  The
latter phrasing might make it clearer that PARSE_OPT_NOARG does not
make an option with an argument that can optionally be left off.

Noticed-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.h

@@ -69,7 +69,7 @@ typedef int parse_opt_cb(const struct option *, const char *arg, int unset);
  * `flags`::
  *   mask of parse_opt_option_flags.
  *   PARSE_OPT_OPTARG: says that the argument is optional (not for BOOLEANs)
- *   PARSE_OPT_NOARG: says that this option takes no argument
+ *   PARSE_OPT_NOARG: says that this option does not take an argument
  *   PARSE_OPT_NONEG: says that this option cannot be negated
  *   PARSE_OPT_HIDDEN: this option is skipped in the default usage, and
  *                     shown only in the full usage.