Spec: Small fix for the number of decommit outputs in fanout tx

spec/onchain.tex

@@ -565,7 +565,7 @@ \subsection{Fan-Out Transaction}
 distributes UTxOs from the head according to the latest state. It consists of
 \begin{itemize}
 	\item one input spending from $\nuHead$ holding the $\st$, and
-	\item outputs $o_{1} \dots o_{m\red{+n}}$ to distribute UTxOs.
+	\item outputs $o_{1} \dots o_{m\red{+m'}}$ to distribute UTxOs.
 \end{itemize}
 
 Note that \mtxFanout{} represents a final transition of the state machine and