Fixed #10954 -- Corrected error in docs example describing extending …

…the JSON serializer. Thanks to Glenn for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10654 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/topics/serialization.txt

@@ -187,7 +187,7 @@ them. Something like this will work::
         def default(self, obj):
             if isinstance(obj, Promise):
                 return force_unicode(obj)
-            return obj
+            return super(LazyEncoder, self).default(obj)
 
 .. _special encoder: http://svn.red-bean.com/bob/simplejson/tags/simplejson-1.7/docs/index.html