Change 'class-modification' -> 'modification' in 'choices-argument'

As suggested by @eshmoylova.

chapters/inheritance.tex

@@ -1003,7 +1003,7 @@ \subsection{Annotations for Suggested Redeclarations and Modifications}\label{an
 "choices" "(" [ choices-argument { "," choice } ] ")"
 
 choices-argument :
-   "choice" class-modification
+   "choice" modification
    | "checkBox" "=" true
 \end{lstlisting}\end{synopsis}
 \begin{semantics}