Comment change.

lisp/progmodes/executable.el

@@ -21,10 +21,13 @@
 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 
 ;;; Commentary:
-
-;; Provide or modify interpreter magic number for buffer, and make file
-;; executable if it isn't.  Support code for the likes of sh-, awk-, perl-,
-;; tcl- or makefile-mode.
+;; This is support code for the likes of sh-, awk-, perl-, tcl- or
+;; makefile-mode.  Those mode-setting commands can call the like of
+;; `(executable-set-magic "sh")' or `(executable-set-magic "perl" "-f")'.
+;; Unless the file name matches `executable-magicless-file-regexp' this will
+;; search $PATH if the given interpreter isn't absolute, and then insert a
+;; first line like `#! /bin/sh' or `#! /usr/local/bin/perl -f' and the file
+;; will be made executable as soon as it's saved if it wasn't.
 
 ;; Would someone please explain clearly what this is to be used for? -- rms.