Apply suggestion: 'A for-equation may optionally use…'

Co-authored-by: Hans Olsson <HansOlsson@users.noreply.github.com>

chapters/equations.tex

@@ -95,7 +95,7 @@ \subsection{For-Equations -- Repetitive Equation Structures}\label{for-equations
    end for ";"
 \end{lstlisting}
 
-\lstinline!for!-equations may optionally use several iterators (\lstinline[language=grammar]!for-indices!)\index{in@\robustinline{in}!for-equation@\robustinline{for}-equation}, see \cref{nested-for-loops-and-reduction-expressions-with-multiple-iterators} for more information:
+A \lstinline!for!-equation may optionally use several iterators (\lstinline[language=grammar]!for-indices!)\index{in@\robustinline{in}!for-equation@\robustinline{for}-equation}, see \cref{nested-for-loops-and-reduction-expressions-with-multiple-iterators} for more information:
 \begin{lstlisting}[language=grammar]
 for-indices:
    for-index {"," for-index}