Correct a statement about indistinguishability of JoinSplit descriptions.

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

protocol/protocol.tex

@@ -1878,8 +1878,8 @@ treated like an \emph{output} value, whereas} $\vpubNew$ is treated like an
 Unlike original \Zerocash \cite{BCG+2014}, \Zcash does not have
 a distinction between Mint and Pour operations. The addition of $\vpubOld$ to a
 \joinSplitDescription subsumes the functionality of both Mint and Pour. Also,
-\joinSplitDescriptions are indistinguishable regardless of the number of real input
-\notes.
+a difference in the number of real input \notes does not by itself cause two
+\joinSplitDescriptions to be distinguishable.
 }
 
 As stated in \crossref{joinsplitdesc}, either $\vpubOld$ or $\vpubNew$ \MUST be zero.
@@ -4135,6 +4135,7 @@ The errors in the proof of Ledger Indistinguishability mentioned in
     \item Clarify the consensus rule preventing double-spends.
     \item Clarify what a \noteCommitment opens to in \crossref{crprf}.
     \item Correct the order of arguments to $\Commit{}$ in \crossref{concretecomm}.
+    \item Correct a statement about indistinguishability of \joinSplitDescriptions.
 \end{itemize}
 
 \introlist