Fix typo in manual.

doc/manual.tex

@@ -1786,7 +1786,7 @@ token, it makes sense for it to \emph{shift} that token.
 \label{fig:reducing:text}
 \end{figure}
 
-In our example, the proof that shifting is possible is the derivation tree
+In our example, the proof that reducing is possible is the derivation tree
 shown in Figures~\ref{fig:reducing:tree} and~\ref{fig:reducing:text}. Again,
 the sentential form found at the fringe of the tree begins with the conflict
 string, followed with the conflict token.