Clean up example "Variables with array dimensions"

Fixes modelica#2855.

(I have checked that the longer lines don't wrap.)

chapters/classes.tex

@@ -180,22 +180,22 @@ \subsection{Component Declaration Static Semantics}\label{component-declaration-
 
 Array dimensions shall be scalar non-negative parameter expressions of type \lstinline!Integer!, a reference to a type (which must an enumeration type or \lstinline!Boolean!, see \cref{enumeration-types}), or the colon operator denoting that the array dimension is left unspecified (see \cref{array-declarations}).  All variants can also be part of short class definitions.
 
-\begin{nonnormative}
-Example of variables with array dimensions.
+\begin{example}
+Variables with array dimensions:
 \begin{lstlisting}[language=modelica]
 model ArrayVariants
-  type T=Real[:];                     // Unspecified size for type
-  parameter T x=ones(4);
-  parameter T y[3]=ones(3, 4);
-  parameter Real a[2]=ones(2);        // Specified using Integer
-  parameter Real b[2, 0]=ones(2, 0);  // Size 0 is allowed
-  parameter Real c[:]=ones(0);        // Unspecified size for variable
-  parameter Integer n=0;
-  Real x[n*2]=cat(1,ones(n),zeros(n)};// Parameter expressions are allowed
-  Boolean notV[Boolean]={true,false}; // Indexing with type
+  type T = Real[:];                       // Unspecified size for type
+  parameter T x = ones(4);
+  parameter T y[3] = ones(3, 4);
+  parameter Real a[2] = ones(2);          // Specified using Integer
+  parameter Real b[2, 0] = ones(2, 0);    // Size 0 is allowed
+  parameter Real c[:] = ones(0);          // Unspecified size for variable
+  parameter Integer n = 0;
+  Real z[n*2] = cat(1, ones(n), zeros(n));// Parameter expressions are allowed
+  Boolean notV[Boolean] = {true, false};  // Indexing with type
 end ArrayVariants;
 \end{lstlisting}
-\end{nonnormative}
+\end{example}
 
 The rules for components in functions are described in \cref{function-as-a-specialized-class}.