Update mailing list links
The mailing list software has been updated and the links have changed.
Signed-off-by: Janos Follath <janos.follath@arm.com>
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b3a9547..10d49cc 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -14,7 +14,7 @@
Making a Contribution
---------------------
-1. [Check for open issues](https://github.com/ARMmbed/mbedtls/issues) or [start a discussion](https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls) around a feature idea or a bug.
+1. [Check for open issues](https://github.com/ARMmbed/mbedtls/issues) or [start a discussion](https://lists.trustedfirmware.org/mailman3/lists/mbed-tls.lists.trustedfirmware.org) around a feature idea or a bug.
1. Fork the [Mbed TLS repository on GitHub](https://github.com/ARMmbed/mbedtls) to start making your changes. As a general rule, you should use the ["development" branch](https://github.com/ARMmbed/mbedtls/tree/development) as a basis.
1. Write a test which shows that the bug was fixed or that the feature works as expected.
1. Send a pull request (PR) and work with us until it gets merged and published. Contributions may need some modifications, so a few rounds of review and fixing may be necessary. We will include your name in the ChangeLog :)