Add a structure of thesis

It is preliminary, but I am almost sure I will stick to it.

en/intro.tex

@@ -105,6 +105,13 @@ Figure~\ref{fig:basic-icons}.
 \section*{Structure of the thesis}
 \addcontentsline{toc}{section}{Structure of the thesis}
 
+In the first chapter, we explore various approaches of visualising and
+monitoring a network system. Then, in chapter \ref{ch:net}, we understand the
+behaviour of relevant networking technologies. From that, we derive a design
+for Bidrvisu in chapter \ref{ch:design}. Chapter \ref{ch:usage} explains usage
+of the program. At the end, we demonstrate how the project works in network
+systems of various sizes.
+
 %- motivation
 %	-tgt audience of birdvisu
 %	- previous work / other approaches to network monitoring