Fixes typo in docs, thanks to anh. Closes #697

docs/whatsnew-2.6.rst

@@ -176,7 +176,7 @@ Tasks can now have callbacks and errbacks, and dependencies are recorded
         >>> from celery import chain
 
         # (2 + 2) * 8 / 2
-        >>> res = chain(add.subtask((4, 4)),
+        >>> res = chain(add.subtask((2, 2)),
                         mul.subtask((8, )),
                         div.subtask((2,))).apply_async()
         >>> res.get() == 16