lisp/window.el (display-buffer): Doc fix.

lisp/ChangeLog

 2012-10-14  Eli Zaretskii  <eliz@gnu.org>
+	* window.el (display-buffer): Doc fix.
+
 	* progmodes/compile.el (compilation-error-regexp-alist-alist):
 	Adjust the msft regexp to the output of Studio 2010, and move msft
 	before edg-1.  See the discussion on emacs-devel,

lisp/window.el

@@ -5361,8 +5361,16 @@ BUFFER-OR-NAME must be a buffer or the name of an existing
 buffer.  Return the window chosen for displaying BUFFER-OR-NAME,
 or nil if no such window is found.
 
-Optional argument ACTION should have the form (FUNCTION . ALIST).
-FUNCTION is either a function or a list of functions.
+Optional argument ACTION, if non-nil, should specify a display
+action.  Its form is described below.
+
+Optional argument FRAME, if non-nil, acts like an additional
+ALIST entry (reusable-frames . FRAME) to the action list of ACTION,
+specifying the frame(s) to search for a window that is already
+displaying the buffer.  See `display-buffer-reuse-window'
+
+If ACTION is non-nil, it should have the form (FUNCTION . ALIST),
+where FUNCTION is either a function or a list of functions, and
 ALIST is an arbitrary association list (alist).
 
 Each such FUNCTION should accept two arguments: the buffer to
@@ -5379,6 +5387,9 @@ function in the combined function list in turn, passing the
 buffer as the first argument and the combined alist as the second
 argument, until one of the functions returns non-nil.
 
+If ACTION is nil, the function list and the alist are built using
+only the other variables mentioned above.
+
 Available action functions include:
  `display-buffer-same-window'
  `display-buffer-reuse-window'
@@ -5407,12 +5418,7 @@ The ACTION argument to `display-buffer' can also have a non-nil
 and non-list value.  This means to display the buffer in a window
 other than the selected one, even if it is already displayed in
 the selected window.  If called interactively with a prefix
-argument, ACTION is t.
-
-Optional argument FRAME, if non-nil, acts like an additional
-ALIST entry (reusable-frames . FRAME), specifying the frame(s) to
-search for a window that is already displaying the buffer.  See
-`display-buffer-reuse-window'."
+argument, ACTION is t."
   (interactive (list (read-buffer "Display buffer: " (other-buffer))
 		     (if current-prefix-arg t)))
   (let ((buffer (if (bufferp buffer-or-name)