Remove redundant non-normative text on extending from operator record

Addressing review comment by Hans.

chapters/classes.tex

@@ -854,11 +854,6 @@ \section{Specialized Classes}\doublelabel{specialized-classes}
 attributes for the component elements directly inside the operator
 record. An operator record can only extend from an operator record. It is not legal to extend
 from any of its enclosing scopes. (See \autoref{overloaded-operators}).
-\par
-\begin{nonnormative*}
-% henrikt-ma 2020-04: This remark seems highly redundant/silly; shouldn't it just be removed?
-An operator record extending from another class will always do this as short class definition, and not from another specialized class.
-\end{nonnormative*}
 \\ \hline
 \lstinline!operator! & Similar to package; but may only contain
 declarations of functions. May only be placed directly in an operator