mbedtls/configs/ext/README.md

Summary
-------

The two files:

* crypto_config_profile_medium.h
* tfm_mbedcrypto_config_profile_medium.h

are copyright The Mbed TLS Contributors, and are distributed under the license normally
used by Mbed TLS: a dual Apache 2.0 or GPLv2-or-later license.

Background
----------

The two files crypto_config_profile_medium.h and tfm_mbedcrypto_config_profile_medium.h
are taken verbatim from the TF-M source code here:

https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/lib/ext/mbedcrypto/mbedcrypto_config

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, with copyright assigned to The Mbed TLS Contributors.

We only retain the note at the top of the files because the intent is to take these files verbatim,
for ease of maintenance. Currently however, they contain changes, showing how these configurations
will need to be adapted for 4.0.