Improved jQuery code

Author: wouterj

cookbook/form/form_collections.rst

@@ -395,7 +395,7 @@ one example:
 
  function addTagForm(collectionHolder, $newLinkLi) {
  // Get the data-prototype explained earlier
- var prototype = collectionHolder.attr('data-prototype');
+ var prototype = collectionHolder.data('prototype');
 
  // get the new index
  var index = collectionHolder.data('index');