Remove the consensus rule "If nJoinSplit > 0, the transaction MUST NOT use SIGHASH types other than SIGHASH_ALL.",

which was never implemented.

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

protocol/protocol.tex

@@ -4043,10 +4043,6 @@ $\MerkleNode{\MerkleDepth}{i}$ is in a tree with a given \merkleRoot $\rt = \Mer
 fields $\nJoinSplit$, $\vJoinSplit$, and (if present) $\joinSplitPubKey$, described in
 \crossref{txnencoding}. They \emph{do not} cover the field $\joinSplitSig$.
 
-\consensusrule{
-If $\nJoinSplit > 0$, the \transaction{} \MUSTNOT use \sighashTypes other than
-$\SIGHASHALL$.
-}
 }
 
 \vspace{3ex}
@@ -8995,6 +8991,15 @@ found by Brian Warner.
 \intropart
 \section{Change History}
 
+\subparagraph{2018.0-beta-21}
+
+\begin{itemize}
+    \item Remove the consensus rule
+          ``If $\nJoinSplit > 0$, the \transaction{} \MUSTNOT use \sighashTypes other than $\SIGHASHALL$.'',
+          which was never implemented.
+\end{itemize}
+
+\introlist
 \subparagraph{2018.0-beta-20}
 
 \begin{itemize}