add chapter for data structure

doc/chapter/2architecture.tex

@@ -86,5 +86,8 @@ For parsing the JSON file the JSON-java library~\cite{leary_json-java:_2018} is
     \label{fig:json-example}
 \end{figure}
 
-\section{Class Diagrams}\label{sec:classDiagrams}
-\TODO{run vpp}
+\section{Internal graph representation}\label{sec:internalGraphRepresentation}
+\TODO{some class diagram}
+
+\section{TODO: More Class Diagrams}\label{sec:classDiagrams}
+\TODO{maybe even into appendix}