DOCS: Replaces broken links

Replaces all links in the docs which have become outdated. This also
includes email addresses which are no longer active.

Change-Id: I6830237c311d2785efd78d5753b8393b1ba06234
Signed-off-by: Matthew Dalzell <matthew.dalzell@arm.com>
diff --git a/docs/design_docs/services/symmetric_initial_attest.rst b/docs/design_docs/services/symmetric_initial_attest.rst
index ca6d2b6..23586b9 100644
--- a/docs/design_docs/services/symmetric_initial_attest.rst
+++ b/docs/design_docs/services/symmetric_initial_attest.rst
@@ -325,7 +325,7 @@
 
 .. [3] :doc:`Initial Attestation Service Integration Guide </integration_guide/services/tfm_attestation_integration_guide>`
 
-.. [4] `t_cose library <https://github.com/laurencelundblade/t_cose/blob/v2.0-alpha-2/inc/t_cose/t_cose_mac_compute.h>`_
+.. [4] `MAC compute in t_cose library <https://github.com/laurencelundblade/t_cose/blob/v2.0-alpha-2/inc/t_cose/t_cose_mac_compute.h>`_
 
 .. [5] `HMAC: Keyed-Hashing for Message Authentication <https://tools.ietf.org/html/rfc2104>`_