fix license (#70)

Author: viviveevee

LICENSE

@@ -192,7 +192,7 @@ recommend that a file or class name and description of purpose be included on
 the same "printed page" as the copyright notice for easier identification
 within third-party archives.
 
-Copyright [yyyy] [name of copyright owner]
+Copyright 2021 DFINITY Foundation
 
 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