Standard compliance.

Author: dunglas

components/serializer.rst

@@ -143,13 +143,13 @@ Attributes Groups
 -----------------
 
 .. versionadded:: 2.7
-    The support of serialization and deserialization groups has been added
+    The support of serialization and deserialization groups was introduced
     in Symfony 2.7.
 
 Sometimes, you want to serialize different set of attributes from your
 entities. Groups are a handy way to achieve this need.
 
-Lets start with a simple Plain Old PHP object::
+Assume you have the following object plain-old-PHP object::
 
     namespace Acme;