[TI] Add title pages

semester3/ti/main/parts/combinatorics.tex

@@ -2,6 +2,8 @@
 \section{Combinatorics}
 \label{sec:combinatorics}
 \subsection{Introduction}
+Please note: This section was not part of the book and is written in very simple terms (it is taken from a summary I wrote 4 years ago during Gymnasium)
+
 Combinatorics was developed from the willingness of humans to gamble and the fact that everybody wanted to win as much money as possible.
 
 \subsection{Simple counting operations}