Minor change in @kindex.

man/frames.texi

@@ -66,7 +66,7 @@ available on MS Windows as of Emacs version 21.1.
 compatible with the @code{xterm} program.  You can use the same mouse
 commands for copying between Emacs and other X client programs.
 
-@kindex DELETE
+@kindex DELETE @r{(and mouse selection)}
   If you select a region with any of these mouse commands, and then
 immediately afterward type the @key{DELETE} function key, it deletes the
 region that you selected.  The @key{BACKSPACE} function key and the