Clarify doc string

* simple.el (toggle-truncate-lines): Clarify what is toggled
(bug#5580).  Text by Drew Adams.

lisp/ChangeLog

+2011-07-13  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* simple.el (toggle-truncate-lines): Clarify what is toggled
+	(bug#5580).  Text by Drew Adams.
+
 2011-07-13  Chong Yidong  <cyd@stupidchicken.com>
 
 	* simple.el (blink-matching-open): Make the error message from the

lisp/simple.el

@@ -5303,11 +5303,12 @@ The variable `selective-display' has a separate value for each buffer."
 (defvaralias 'indicate-unused-lines 'indicate-empty-lines)
 
 (defun toggle-truncate-lines (&optional arg)
-  "Toggle whether to fold or truncate long lines for the current buffer.
+  "Toggle truncating of long lines for the current buffer.
+When truncating is off, long lines are folded.
 With prefix argument ARG, truncate long lines if ARG is positive,
-otherwise don't truncate them.  Note that in side-by-side windows,
-this command has no effect if `truncate-partial-width-windows'
-is non-nil."
+otherwise fold them.  Note that in side-by-side windows, this
+command has no effect if `truncate-partial-width-windows' is
+non-nil."
   (interactive "P")
   (setq truncate-lines
 	(if (null arg)