corrected typo

manual/opencs/filters.tex

@@ -82,7 +82,7 @@ As you would imagine the range can be specified as including a border value, or
  \item Mixing brackets is completely legal. For value equal 10, expression value(something, [5, 10) will evaluate to true. The same expression will evaluate to false for value equal 10.
 \end{itemize}
 
-\susubbsection{Logical expressions}
+\subsubsection{Logical expressions}
 This subsection takes care of two remaining groups of expressions: binary and unary. The only unary expression present in the OpenCS is logical not, while the remaining binary expressions are: or, and. This clearly makes theme from user point of view belonging to the same group of logical expressions.
 
 \paragraph{not -- not expression()}