Fix code license, add NOTICE (open-telemetry#3678)

Co-authored-by: Phillip Carter <[email protected]>

Author: svrnm

LICENSE-CODE

@@ -187,9 +187,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright 2020 The KEDA Authors.
-
-   and others that have contributed code to the public domain.
+   Copyright [yyyy] [name of copyright owner]
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.