\ell_Merkle is a bit length, not a byte length.

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

protocol/protocol.tex

@@ -1233,7 +1233,7 @@ entered into the \noteCommitmentTree associated with the previous \block.
 \todo{Make this more precise.}
 
 Each \merkleNode in the \incrementalMerkleTree is associated with a \merkleHash of
-size $\MerkleHashLength$ bytes.
+size $\MerkleHashLength$ bits.
 The \merkleLayer numbered $h$, counting from \merkleLayer $0$ at the \merkleRoot, has
 $2^h$ \merkleNodes with \merkleIndices $0$ to $2^h-1$ inclusive.
 The \merkleHash associated with the \merkleNode at \merkleIndex $i$ in \merkleLayer $h$
@@ -4033,6 +4033,13 @@ The errors in the proof of Ledger Indistinguishability mentioned in
 \introlist
 \nsection{Change history}
 
+\subparagraph{2017.0-beta-2.1}
+
+\begin{itemize}
+    \item $\MerkleHashLength$ is a bit length, not a byte length.
+\end{itemize}
+
+\introlist
 \subparagraph{2017.0-beta-2}
 
 \begin{itemize}