Update Change History for 2018.0-beta-12.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

protocol/protocol.tex

@@ -7222,6 +7222,26 @@ Daira Hopwood, Sean Bowe, and Jack Grigg.
 \introsection
 \nsection{Change History}
 
+\subparagraph{2018.0-beta-12}
+
+\begin{itemize}
+    \item No changes to \Sprout.
+\nuzero{
+    \item Add references to \NUZero ZIPs and update the section on
+          \NUZero/\Sapling transitions.
+}
+\sapling{
+    \item Add a section on re-randomizable signatures.
+    \item Add definition of $\PRFnr{}$.
+    \item Work-in-progress on \Sapling statements.
+    \item Rename \quotedterm{raw} to \quotedterm{homomorphic} \xPedersenCommitments.
+    \item Add packing modulo the field size and range checks to Appendix A.
+    \item Update the algorithm for variable-base scalar multiplication to
+          what is implemented by sapling-crypto.
+}
+\end{itemize}
+
+\introlist
 \subparagraph{2018.0-beta-11}
 
 \begin{itemize}