mention `delete-trailing-whitespace'

etc/NEWS

@@ -41,6 +41,10 @@ lacks unexec, asynchronous processes, and networking support.
 
 * Changes in Emacs 21.1
 
+** The new command M-x delete-trailing-whitespace RET will delete the
+traling whitespace within the current restriction.  You can also add
+this function to `write-file-hooks' or `local-write-file-hooks'.
+
 ** When visiting a file with M-x find-file-literally, no newlines will
 be added to the end of the buffer because of `require-final-newline'.
 
@@ -884,7 +888,7 @@ font-lock keywords from the current buffer or from a specific major mode.
 
 *** `font-lock-syntactic-face-function' allows major-modes to choose
 the face used for each string/comment.
-	
+
 ** Comint (subshell) changes
 
 These changes generally affect all modes derived from comint mode, which
@@ -964,7 +968,7 @@ in which folder to put messages automatically.
 *** M-f and M-p jump around \begin...\end pairs.
 
 *** Added support for outline-minor-mode.
-	
+
 ** Changes to RefTeX mode
 
 *** RefTeX has new support for index generation.  Index entries can be
@@ -1589,7 +1593,7 @@ Features are:
 
 - Intersecting: When a `|' intersects with a `-', a `+' is
   drawn, like this:   |         \ /
-                    --+--        X 
+                    --+--        X
                       |         / \
 
 - Rubber-banding: When drawing lines you can interactively see the
@@ -1609,7 +1613,7 @@ Features are:
   regions.  Artist also interfaces with the rect package (this can be
   turned off if it causes you any trouble) so anything you cut in
   artist can be yanked with C-x r y and vice versa.
-  
+
 - Drawing with keys: Everything you can do with the mouse, you can
   also do without the mouse.