Fixed wrong section level.

git-svn-id: svn://svn.code.sf.net/p/rodin-b-sharp/svn/trunk/Handbook@14612 1434b563-b632-4741-aa49-43a3a8374d2e

org.rodinp.handbook.feature/latex/reference-01.tex

@@ -728,7 +728,7 @@ This window allows the user to keep track of recently manipulated (i.e. used, re
 
 Operations similar to those in the \textsf{Selected Hypotheses} and \textsf{Search Hypotheses} views are also available for the cached hypotheses. It is possible to remove, select, and start a proof by contradiction (\icon{rodin/falsify_prover.png}) in the \textsf{Cache Hypotheses} view as well. Interactive proof steps (e.g., rewriting) can also be carried out in the \textsf{Cache Hypotheses} view.
 
-\subsection{The Type Environment View}
+\subsubsection{The Type Environment View}
 
 \begin{figure}[!ht]
 \begin{center}