Add more detailed Postgres license info.

LICENSE.POSTGRESQL

@@ -0,0 +1,28 @@
+This project includes code derived from the PostgreSQL project (http://www.postgresql.org/),
+see the original full copyright notice below:
+
+---
+
+PostgreSQL Database Management System
+(formerly known as Postgres, then as Postgres95)
+
+Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
+
+Portions Copyright (c) 1994, The Regents of the University of California
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose, without fee, and without a written agreement
+is hereby granted, provided that the above copyright notice and this
+paragraph and the following two paragraphs appear in all copies.
+
+IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
+DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
+LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
+DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO
+PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

README.md

@@ -106,5 +106,5 @@ You can find all the node struct types in the `nodes/` directory.
 Copyright (c) 2015, Lukas Fittl <[email protected]><br>
 pg_query.go is licensed under the 3-clause BSD license, see LICENSE file for details.
 
-Query normalization code:<br>
-Copyright (c) 2008-2015, PostgreSQL Global Development Group
+This project includes code derived from the [PostgreSQL project](http://www.postgresql.org/),
+see LICENSE.POSTGRESQL for details.