doc: Expand contact information in About section

Giving a bit more background information about the issue tracker
and mailing lists.

Change-Id: I68921d54e3113d348f1e16c685f74d32df2ca19f
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

docs/about/contact.rst

 Support & Contact
 -----------------
 
-We welcome any feedback on TF-A. If you think you have found a security
-vulnerability, please report this using the process defined in the TF-A
-:ref:`Security Handling` document.
+We welcome any feedback on |TF-A| and there are several methods for providing
+it or for obtaining support.
 
-For all other feedback, please use the `issue tracker`_ or our `mailing list`_.
+.. warning::
+  If you think you have found a security vulnerability, please report this using
+  the process defined in the :ref:`Security Handling` document.
 
-Arm licensees may contact Arm directly via their partner managers.
+Mailing Lists
+^^^^^^^^^^^^^
 
-.. _issue tracker: https://issues.trustedfirmware.org
-.. _mailing list: https://lists.trustedfirmware.org/mailman/listinfo/tf-a
+Public mailing lists for TF-A and the wider Trusted Firmware project are
+hosted on TrustedFirmware.org. The mailing lists can be used for general
+enquiries, enhancement requests and issue reports, or to follow and participate
+in technical or organizational discussions around the project. These discussions
+include design proposals, advance notice of changes and upcoming events.
+
+The relevant lists for the TF-A project are:
+
+-  `TF-A development`_
+-  `TF-A-Tests development`_
+
+You can see a `summary of all the lists`_ on the TrustedFirmware.org website.
+
+Issue Tracker
+^^^^^^^^^^^^^
+
+Specific issues may be raised using the `issue tracker`_ on the
+TrustedFirmware.org website. Using this tracker makes it easy for the
+maintainers to prioritise and respond to your ticket.
+
+Arm Licensees
+^^^^^^^^^^^^^
+
+Arm licensees have an additional support conduit - they may contact Arm directly
+via their partner managers.
+
+.. _`issue tracker`: https://developer.trustedfirmware.org
+.. _`TF-A development`: https://lists.trustedfirmware.org/pipermail/tf-a/
+.. _`TF-A-Tests development`: https://lists.trustedfirmware.org/pipermail/tf-a-tests/
+.. _`summary of all the lists`: https://lists.trustedfirmware.org
 
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