Miscellaneous doc fixes/enhancements

Change-Id: I915303cea787d9fb188428b98ac6cfc610cc4470
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/docs/auth-framework.rst b/docs/auth-framework.rst
index e0b569f..a46f946 100644
--- a/docs/auth-framework.rst
+++ b/docs/auth-framework.rst
@@ -720,7 +720,7 @@
 
 Four image descriptors form the BL31 Chain of Trust:
 
-.. code:: asm
+.. code:: c
 
     [TRUSTED_KEY_CERT_ID] = {
         .img_id = TRUSTED_KEY_CERT_ID,