Mention copyright in the readme

Signed-off-by: Dave Rodgman <[email protected]>

configs/ext/README.md

@@ -2,7 +2,7 @@ Summary
 -------
 
 All files in this directory are distributed under the normal Mbed TLS dual Apache 2.0 or GPLv2-or-later
-license.
+license, and are copyright The Mbed TLS Contributors.
 
 Background
 -----------
@@ -14,7 +14,7 @@ https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/lib/ext/mbedcry
 
 In TF-M, they are distributed under a 3-Clause BSD license, as noted at the top of the files.
 
-In Mbed TLS, with permission from the TF-M project, they are distributed under a dual [Apache-2.0](https://spdx.org/licenses/Apache-2.0.html) OR [GPL-2.0-or-later](https://spdx.org/licenses/GPL-2.0-or-later.html) license.
+In Mbed TLS, with permission from the TF-M project, they are distributed under a dual [Apache-2.0](https://spdx.org/licenses/Apache-2.0.html) OR [GPL-2.0-or-later](https://spdx.org/licenses/GPL-2.0-or-later.html) license, with copyright assigned to The Mbed TLS Contributors.
 
 We only retain the note at the top of the files because we are taking the files un-modified, for ease of
 maintenance.