update changelog

Author: xabbuh

CHANGELOG.md

@@ -4,7 +4,8 @@ CHANGELOG
 2.7.2
 -----
 
-* fix compatibility with `null` owner returned by SensioFrameworkExtraBundle (#2097)
+* fixed serializing Error instances when JMS Serializer is used (#2105)
+* fixed compatibility with `null` owner returned by SensioFrameworkExtraBundle (#2097)
 * completely fixed handling `Throwable` objects in `ExceptionController::showAction()`,
   continues #2093 (#2096)