Apply suggestions from code review

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

chapters/equations.tex

@@ -819,8 +819,9 @@ \section{Initialization, initial equation, and initial algorithm}\label{initiali
 
 It may be difficult for a user to figure out how many initial equations have to be added, especially if the system has a higher index.
 \end{nonnormative}
+
 Based on these non-normative considerations we have the following rules:
-A tool may add or remove initial equations automatically such that the resulting system is structurally nonsingular.
+A tool may add or remove initial equations automatically according to the rules below such that the resulting system is structurally nonsingular.
 In these cases diagnostics are appropriate since the result is not unique and not necessarily what the user expects.
 \begin{itemize}
 \item A missing initial value of a discrete-time variable which does not influence the simulation result, may be automatically set to the start value or its default without informing the user.