Add missing styling of 'packageprefixname'

chapters/packages.tex

@@ -264,7 +264,7 @@ \subsection{The within Clause}\label{the-within-clause}
 
 \begin{example}
 The subpackage \lstinline!Rotational! declared within \lstinline!Modelica.Mechanics! has the fully qualified name
-\lstinline!Modelica.Mechanics.Rotational!, which is formed by concatenating the packageprefixname with the short name of the package.
+\lstinline!Modelica.Mechanics.Rotational!, which is formed by concatenating the \lstinline[language=grammar]!packageprefixname! with the short name of the package.
 The declaration of \lstinline!Rotational! could be given as below:
 \begin{lstlisting}[language=modelica]
 within Modelica.Mechanics;