Describe next- and prev-buffer.

Warn about change of keybindings for winner-redo and -undo.
Describe help argument highlighting feature.

etc/NEWS

@@ -90,6 +90,16 @@ types any more.  Add -DUSE_LISP_UNION_TYPE if you want union types.
 
 * Changes in Emacs 21.4
 
+** Convenient commands to switch buffers in a cyclic order are C-x <left>
+(prev-buffer) and C-x <right> (next-buffer).
+
+** Commands winner-redo and winner-undo, from winner.el, are now bound to
+C-c <left> and C-c <right>, respectively.  This is an incompatible change.
+
+** Help commands `describe-funcion' and `describe-key' now show function
+arguments in italics.  To change the default highlighting customize the
+face `help-argument-name'.
+
 ---
 ** The comint prompt can now be made read-only, using the new user
 option `comint-prompt-read-only'.  This is not enabled by default,