Clarify in README.md that 'the project' is Mbed TLS

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/README.md b/README.md
index cbdb2df3..449be1e 100644
--- a/README.md
+++ b/README.md
@@ -313,7 +313,7 @@
 This project contains code from other projects. This code is located within the `3rdparty/` directory. The original license text is included within project subdirectories, and in source files. The projects are listed below:
 
 * `3rdparty/everest/`: Files stem from [Project Everest](https://project-everest.github.io/) and are distributed under the Apache 2.0 license.
-* `3rdparty/p256-m/p256-m/`: Files have been taken from the [p256-m](https://github.com/mpg/p256-m) repository. The code in the original repository is distributed under the Apache 2.0 license. It is also used by the project under the Apache 2.0 license. We do not plan to regularly update these files, so they may not contain fixes and improvements present in the upstream project.
+* `3rdparty/p256-m/p256-m/`: Files have been taken from the [p256-m](https://github.com/mpg/p256-m) repository. The code in the original repository is distributed under the Apache 2.0 license. It is also used by Mbed TLS under the Apache 2.0 license. We do not plan to regularly update these files, so they may not contain fixes and improvements present in the upstream project.
 
 Contributing
 ------------