Fix: broken link to TS email list in documentation

Mailman was updated to a newer version and the URL of the web API of
the mailing list did change. This patch fixes the URL in the
documentation.

Change-Id: Ifb71bf2712c265e9cd62b8746d3651caf04c0a77
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
diff --git a/docs/global_substitutions.txt b/docs/global_substitutions.txt
index 7ec8d74..3e74ba7 100644
--- a/docs/global_substitutions.txt
+++ b/docs/global_substitutions.txt
@@ -12,13 +12,13 @@
 .. |PSA| replace:: :term:`PSA`
 .. |FF-A| replace:: :term:`FF-A`
 
-.. _`TS Mailing List`: https://lists.trustedfirmware.org/mailman/listinfo/trusted-services
+.. _`TS Mailing List`: https://lists.trustedfirmware.org/mailman3/lists/trusted-services.lists.trustedfirmware.org/
 .. _`TS repository`: https://review.trustedfirmware.org/admin/repos/TS/trusted-services
 .. _`Semantic Versioning`: https://semver.org/spec/v2.0.0.html
 
 ..
    --------------
 
-   *Copyright (c) 2020-2021, Arm Limited and Contributors. All rights reserved.*
+   *Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.*
 
    SPDX-License-Identifier: BSD-3-Clause