Don't speak of overriding non-final displayUnit

As suggested by Hans.

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

chapters/classes.tex

@@ -1553,7 +1553,7 @@ \subsection{Real Type}\label{real-type}
 
 \begin{nonnormative}
 That \lstinline!displayUnit! is evaluable allows tools to verify that the default display unit is consistent with the \lstinline!unit!.
-Unlike the \lstinline!unit!, \lstinline!displayUnit! is just a default and unless given by a final modification, tools may allow overriding the default with other compatible display units in a translated model.
+Unlike the \lstinline!unit!, \lstinline!displayUnit! is just a default, tools may allow using other compatible display units for a translated model.
 \end{nonnormative}
 
 The \lstinline!nominal! attribute is meant to be used for scaling purposes and to