Docs: Update the TF-M Crypto service design doc

Update the TF-M Crypto service design document
to reflect significant changes introduced in
the service architecture in TF-Mv2.1.0.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I7b8dbb6860280994a48dc3b4bb41d274fbd8186b
diff --git a/docs/design_docs/tfm_builtin_keys.rst b/docs/design_docs/tfm_builtin_keys.rst
index 0ea583d..b500932 100644
--- a/docs/design_docs/tfm_builtin_keys.rst
+++ b/docs/design_docs/tfm_builtin_keys.rst
@@ -1,3 +1,5 @@
+.. _tfm-builtin-keys-label:
+
 #################
 TF-M builtin keys
 #################
@@ -6,8 +8,6 @@
 :Organization: Arm Limited
 :Contact: raef.coles@arm.com
 
-.. _tfm-builtin-keys-label:
-
 ************
 Introduction
 ************
@@ -259,7 +259,7 @@
 References
 **********
 
-.. [1] PSA cryptoprocessor driver interface: \ https://github.com/Mbed-TLS/mbedtls/blob/development/docs/proposed/psa-driver-interface.md
+.. [1] PSA cryptoprocessor driver interface: \ https://github.com/Mbed-TLS/mbedtls/blob/development/docs/proposed/psa-driver-interface.md
 .. [2] Definition of psa_key_location_t type in the PSA spec: \ https://arm-software.github.io/psa-api/crypto/1.1/api/keys/lifetimes.html#c.psa_key_location_t
 .. [3] Interface for platform keys: \ https://github.com/ARM-software/psa-crypto-api/issues/550