2014-04-24: fix wisp example in why-wisp

fix wisp example in why-wisp

diff --git a/docs/why-wisp.org b/docs/why-wisp.org
--- a/docs/why-wisp.org
+++ b/docs/why-wisp.org
@@ -243,7 +243,7 @@ becomes
   ((x 1)
    (y 2)
    (z 3))
-  body)
+  (body))
 #+END_SRC