remove extraneous word

synchro.tex

@@ -429,7 +429,7 @@
 \texttt{fcntl}, specifies only how to lock and how many bytes from the current
 position in the file. Very often implemented as \texttt{fcntl} wrapper.
 Beware: one cannot assume it is implemented around \texttt{fcntl} therefore
-avoid using these both together.
+avoid using these together.
 \item The example \example{file-locking/lockf.c} demonstrates how mandatory
 locking works and the use of the \texttt{lockf} function.
 \end{itemize}