trivial rewording in footnote 5.

Doc/lib/libstdtypes.tex

@@ -856,8 +856,8 @@ Notes:
 
 \item[(5)] The \method{sort()} and \method{reverse()} methods modify the
   list in place for economy of space when sorting or reversing a large
-  list.  They don't return the sorted or reversed list to remind you
-  of this side effect.
+  list.  To remind you that they operate by side effect, they don't return
+  the sorted or reversed list.
 
 \item[(6)] The \method{sort()} method takes an optional argument
   specifying a comparison function of two arguments (list items) which