Updating component declarations to allow indexing with types.

Note that the text was slightly changed to group "an enumeration type and Boolean" together so that they both can refer to the same section.
Part of #2221

chapters/classes.tex

@@ -191,9 +191,10 @@ \subsection{Component Declaration Static Semantics}\doublelabel{component-declar
 \end{itemize}
 in that order.
 
-Array dimensions shall be non-negative parameter expressions, or the
-colon operator denoting that the array dimension is left unspecified.
-Both variants can also be part of short class definitions.
+Array dimensions shall be scalar non-negative parameter expressions of type Integer, 
+a reference to a type (which must an enumeration type or Boolean, see \autoref{enumeration-types}), 
+or the colon operator denoting that the array dimension is left unspecified.
+All variants can also be part of short class definitions.
 
 \begin{nonnormative}
 Example of variables with array dimensions.