In \crossref{joinsplit}, clarify that balance for JoinSplit transfers…

… is enforced by the

JoinSplit statement, and that there is no consensus rule to check it directly.

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

protocol/protocol.tex

@@ -3439,10 +3439,11 @@
 it is not known where it will eventually appear in a mined \block. Therefore the
 \anchors that it uses must be independent of its eventual position.
 
+The input and output values of each \joinSplitTransfer \MUST balance exactly. This
+is not a consensus rule since it cannot be checked directly; it is enforced by the
+\snarkref{Balance}{sproutbalance} rule of the \joinSplitStatement.
+
 \begin{consensusrules}
-  \item The input and output values of each \joinSplitTransfer \MUST balance
-        exactly.
-        \vspace{-0.5ex}
   \item For the first \joinSplitDescription of a \transaction, the \anchor \MUST
         be the output \Sprout \treestate of a previous \block.
         \vspace{-0.5ex}
@@ -14519,6 +14520,13 @@
 \lsection{Change History}{changehistory}
 
 
+\historyentry{2022.2.19}{}
+\begin{itemize}
+    \item In \crossref{joinsplit}, clarify that balance for \joinSplitTransfers is enforced
+          by the \joinSplitStatement, and that there is no consensus rule to check it directly.
+\end{itemize}
+
+
 \historyentry{2022.2.18}{2022-01-03}
 \begin{itemize}
 \nufive{