Fix CVE number in History

Author: drbrain

History.txt

@@ -2,7 +2,7 @@
 
 * Bug fixes
   * Fixed an XSS exploit in darkfish.js.  This could lead to cookie disclosure
-    to third parties.  See CVE-2012-0256.rdoc for full details including a
+    to third parties.  See CVE-2013-0256.rdoc for full details including a
     patch you can apply to generated RDoc documentation.
 
 === 3.9.4 / 2011-08-26