Clarify copyright and license of Migrate

LICENSE.md

@@ -224,4 +224,18 b' in this distribution.'
 
 
 
+Migrate
+-------
+
+Kallithea incorporates in rhodecode/lib/dbmigrate/migrate parts of the Python
+system called [Migrate or sqlalchemy-migrate](https://github.com/stackforge/sqlalchemy-migrate),
+which is:
+
+Copyright (c) 2009 Evan Rosson, Jan Dittberner, Domen Kožar
+
+and licensed under the MIT-permissive license, which is
+[included in this distribution](MIT-Permissive-License.txt).
+
+
+
 EOF