Update data.md

Author: juukie

docs/en/pipeline/data.md

@@ -56,7 +56,7 @@ By returning a Promise:
 
 ``` js
 route: {
-  data: function () {
+  data: function (transition) {
     return messageService
       .fetch(transition.to.params.messageId)
       .then(function (message) {