Add note about workaround

Closes modelica#3024

chapters/operatorsandexpressions.tex

@@ -104,6 +104,7 @@ \section{Operator Precedence and Associativity}\label{operator-precedence-and-as
 +$\hspace{0pt}$+2  // = 2 in Mathematica/MATLAB; is illegal in Modelica
 2-$\hspace{0pt}$-2 // = 4 in Mathematica/MATLAB; is illegal in Modelica
 \end{lstlisting}
+% Using $\hspace{0pt}$ to work around https://github.com/brucemiller/LaTeXML/issues/1399
 
 Non-associative exponentiation and array range operator (note that the array range operator only takes scalar operands):
 \begin{lstlisting}[language=modelica]