virtio-msg: clarify the FF-A bus bibliography reference

Reference the Virtio Message Bus over FF-A specification through the
normative bibliography using a distinct FFA-BUS citation tag.

Attribute the DEN0153 document to Arm and keep the transport chapter
citing the bibliography entry instead of a raw URL.

Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>

Author: bertrand-marquis

introduction.tex

@@ -92,6 +92,9 @@ \section{Normative References}\label{sec:Normative References}
 	\phantomsection\label{intro:I2C}\textbf{[I2C]} &
 	I2C-bus specification and user manual,
 	\newline\url{https://www.nxp.com/docs/en/user-guide/UM10204.pdf}\\
+	\phantomsection\label{intro:FFA-BUS}\textbf{[FFA-BUS]} &
+	Arm, Virtio Message Bus over FF-A, DEN0153,
+	\newline\url{https://developer.arm.com/documentation/den0153/0101/}\\
 	\phantomsection\label{intro:SCMI}\textbf{[SCMI]} &
 	Arm System Control and Management Interface, DEN0056,
 	\newline\url{https://developer.arm.com/docs/den0056/c}, version C and any future revisions\\
@@ -350,4 +353,3 @@ \section{Constant Specifications}\label{sec:Constant Specifications}
 either VIRTIO_FLD_A or VIRTIO_FLD_B.
 
 \newpage
-

transport-msg.tex

@@ -147,8 +147,8 @@ \subsubsection{Known Bus Implementation Examples}
 work for virtio-msg.
 
 \begin{itemize}
-  \item \textbf{Virtio Message Bus over FF-A}: specified by Arm DEN0153:
-        \url{https://developer.arm.com/documentation/den0153/latest}.
+  \item \textbf{Virtio Message Bus over FF-A}: specified by Arm in
+        \hyperref[intro:FFA-BUS]{[FFA-BUS]}.
   \item \textbf{Virtio Message Bus over PCI for AMP}: under development; proof
         of concept:
         \url{https://github.com/wmamills/hvac-demo}.