Reference markup fix.

pep-3100.txt

@@ -65,7 +65,7 @@ Core language
 
 * True division becomes default behavior [#pep238]_ [done]
 * ``exec`` as a statement is not worth it -- make it a function [done]
-* (Maybe) add optional declarations for static typing [#pep3107] [10]_
+* (Maybe) add optional declarations for static typing [#pep3107]_ [10]_
 * Support only new-style classes; classic classes will be gone [1]_ [done]
 * Replace ``print`` by a function [14]_  [#pep3105]_
 * Use ``except E1, E2, E3 as err:`` if you want the error variable. [3]_