Docs: Update broken URLs

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I9649113504e174d0f1e8d2b59eb731d0d26c87f6
diff --git a/docs/contributing/contributing_process.rst b/docs/contributing/contributing_process.rst
index 95afef0..fb2379b 100644
--- a/docs/contributing/contributing_process.rst
+++ b/docs/contributing/contributing_process.rst
@@ -8,9 +8,9 @@
    Please contact :doc:`maintainers </contributing/maintainers>` for any
    questions.
 
-- Subscribe to `TF-M development
-  <https://lists.trustedfirmware.org/mailman/listinfo/tf-m>`_ if not subscribed
-  already.
+- Subscribe to `TF-M development mailing list
+  <https://lists.trustedfirmware.org/mailman3/lists/tf-m.lists.trustedfirmware.org>`_
+  if not subscribed already.
 - Refer to the `Roadmap
   <https://developer.trustedfirmware.org/w/tf_m/planning>`_ or send a mail to
   the tf-m@lists.trustedfirmware.org to check if this work is already