Improve changelog

Author: alex-kulakov

ChangeLog/6.0.12_dev.txt

@@ -1,4 +1,5 @@
 [main] Addressed DataTypeCollection.Add method issue of wrong adding storage-specifid types to the collection
 [main] Addressed rare issue of entities expire management when SessionOption.NonTransactionalReads is on
 [main] Fixed issue of skipping persist or query tasks during batching
+[main] Improved error message when the entity user operates with is removed, now it contains type of entity
 [sqlserver] Sql error messages for British English are correctly parsed