docs: update links to tf.org-wide process documents

tf.org-wide documents have been migrated away from
developer.trustedfirmware.org, because the latter will be
decomissioned at some point in the future. These documents are now
hosted in a new 'tf_docs' repository hosted on Github [1] and can be
easily browsed through a new ReadTheDocs website at [2].

Update all relevant links in TF-A documentation to refer to [2].

[1] https://github.com/TrustedFirmware/tf_docs
[2] https://trusted-firmware-docs.readthedocs.io/

Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Change-Id: Ib9d39c36250a05754fe5e46cb6f3044ecb776534
diff --git a/docs/process/security.rst b/docs/process/security.rst
index c6429ad..bbc939a 100644
--- a/docs/process/security.rst
+++ b/docs/process/security.rst
@@ -88,7 +88,7 @@
 .. |TFV-9| replace:: :ref:`Advisory TFV-9 (CVE-2022-23960)`
 .. |TFV-10| replace:: :ref:`Advisory TFV-10 (CVE-2022-47630)`
 
-.. _TrustedFirmware.org security incident process: https://developer.trustedfirmware.org/w/collaboration/security_center/
+.. _TrustedFirmware.org security incident process: https://trusted-firmware-docs.readthedocs.io/en/latest/security_center/
 
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