Fix copy past error, wrong license header

doc.go

@@ -1,17 +1,8 @@
 /*
- * Copyright 2017 Kopano and its licensors
+ * Copyright 2017 Kopano
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * Use of this source code is governed by a MIT license
+ * that can be found in the LICENSE.txt file.
  *
  */