Add license info.

README.md

@@ -58,3 +58,23 @@ optional arguments:
                         Specify starting address (defaults to 0)
 
   -i, --invalid         Show invalid opcodes as ??? rather than constants
+
+Files written by me are released under the following license:
+
+Copyright (C) by Jeff Tranter <tranter@pobox.com>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Documentation written by me is licensed under a Creative Commons
+Attribution 4.0 International License.
+See https://creativecommons.org/licenses/by/4.0/