Update to release notes

Author: fredericDelaporte

releasenotes.txt

@@ -22,6 +22,8 @@
     ##### Possible Breaking Changes #####
         * All members exposing some System.Data types have been changed for corresponding System.Data.Common
           types. (IDbCommand => DbCommand, ...)
+        * The Date NHibernate type will no more replace by null values below its base value (which was year 1753).
+          Its base value is now DateTime.MinValue. Its configuration parameter is obsolete.
         * Transaction scopes handling has undergone a major rework. See NH-4011 for full details.
           ** More transaction promotion to distributed may occur if you use the "flush on commit" feature with
              transaction scopes. Explicitly flush your session instead. Ensure it does not occur by disabling
@@ -77,6 +79,7 @@
 
 ** Bug
     * [NH-926] - Identity insert fails with SQL Ce dialect and aggressive connection release mode.
+    * [NH-1752] - NHibernate Date type converts to NULL
     * [NH-1904] - Protected properties and public properties cannot have the same name with different case
     * [NH-2029] - filter-def's use-many-to-one=false should take ON into consideration
     * [NH-2145] - AssertionFailure exception at ISession.Save