Adding deserialization notes to Changelog

Changelog.rst

@@ -24,6 +24,9 @@ Release compatible with elasticsearch 6.0, changes include:
 
  * methods on ``connections`` singleton are now exposed on the ``connections``
    module directly.
+ * field values are now only deserialized when coming from elasticsearch (via
+   ``from_es`` method) and not when assigning values in python (either by
+   direct assignment or in ``__init__``).
 
 5.4.0 (2017-12-06)
 ------------------

docs/persistence.rst

@@ -150,7 +150,7 @@ If you want to create a model-like wrapper around your documents, use the
 
         def add_comment(self, author, content):
             self.comments.append(
-              {'author': author, 'content': content})
+              Comment(author=author, content=content, created_at=datetime.now()))
 
         def save(self, ** kwargs):
             self.created_at = datetime.now()