Add suggested 'A' at start of sentence

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

chapters/equations.tex

@@ -401,7 +401,7 @@ \subsubsection{Application of the Single-assignment Rule to When-Equations}\labe
 \end{nonnormative}
 
 \item
-  \lstinline!when!-equations involving elsewhen-parts can be used to resolve assignment conflicts since the first of the when/elsewhen parts are given higher priority than later ones:
+  A \lstinline!when!-equation involving elsewhen-parts can be used to resolve assignment conflicts since the first of the when/elsewhen parts are given higher priority than later ones:
 \begin{nonnormative}
 Below it is well defined what happens if both conditions
 become \lstinline!true! at the same time instant since \lstinline!condition1! with