change formatting

Co-authored-by: Henrik Tidefelt <henrikt@wolfram.com>

chapters/packages.tex

@@ -356,7 +356,7 @@ \section{Multilingual Descriptions}\label{multilingual-descriptions}
 Comments start with an \lstinline!#! and are continued until the end of line.
 Spaces outside strings are ignored and used as separators.
 
-The header is marked with an empty \emph{msgid} entry and looks like this:
+The header is marked with an empty \lstinline!msgid! entry and looks like this:
 \begin{lstlisting}
 # SOME DESCRIPTIVE TITLE.
 # Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER