[doc] Remove section about outdated highlighting file

doc/handbook/4_externaltools.tex

@@ -43,13 +43,6 @@ Then rerun cmake (in the second case set \texttt{GSTAT\_ROOT} in your input file
 path where gstat is installed).
 
 
-\subsection{Kate}
-For kate there is syntax highlighting style for \Dumux input files. Simply
-copy the file \texttt{dumux-devel/dumux\-InputFiles.xml} to the \texttt{syntax} folder in
-your kate configuration directory (e.g.
-\texttt{HOME/.kde4/share/apps\-/katepart/syntax/dumuxInputFiles.xml}).
-
-
 \subsection{ParaView}
 \paragraph{Reload Button:}
 There are scripts to reload \texttt{*.pvd} or series of {\texttt{*.vtu} files since ParaView 4.2.