Specify copyright holders in main license file (pydata#9756)

* new blank whatsnew

* specify copyright holders in license text

* update year in readme

Author: TomNicholas

LICENSE

@@ -176,7 +176,7 @@ 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 2014-2024 xarray Developers
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

README.md

@@ -108,7 +108,7 @@ Thanks to our many contributors!
 
 ## License
 
-Copyright 2014-2023, xarray Developers
+Copyright 2014-2024, xarray Developers
 
 Licensed under the Apache License, Version 2.0 (the "License"); you
 may not use this file except in compliance with the License. You may