[handbook] Move passage about guidelines and delete .tex file

doc/handbook/0_dumux-handbook.tex

@@ -126,14 +126,13 @@ how to build the documentation and about external libraries and modules.
 \chapter{Overview and Infrastructure}
 This chapter provides an overview of the general structure in \Dumux \ref{sc_structure}
 and gives help for basic work with \Dumux
-(\ref{sc_newfoldersetup},\ref{sc_parameterfiles},\ref{sc_restartsimulations},\ref{sc_guidelines},\ref{sc_developingdumux}).
+(\ref{sc_newfoldersetup},\ref{sc_parameterfiles},\ref{sc_restartsimulations}, \ref{sc_developingdumux}).
 Further it presents useful external tools \ref{sc_externaltools} and basic
 concepts \ref{sc_linearsystem}.
 \input{4_structure}
 \input{4_newfoldersetup}
 \input{4_parameterfiles}
 \input{4_restartsimulations}
-\input{4_guidelines}
 \input{4_developingdumux}
 \input{4_externaltools}
 \input{4_assemblinglinearsystem}