Clarify that "final x=break" cannot be overriden.

Closes modelica#3310

chapters/inheritance.tex

@@ -573,7 +573,7 @@ \subsection{Removing Modifiers -- break}\label{removing-modifiers-break}
 The modifiers using \lstinline!break! are merged using the same rule as other modifications, and follow the same restrictions so they cannot override a final modifier.
 During flattening of an instantiated model, remaining \lstinline!break! modifications (i.e., the ones that are not further overriden) are treated as if the expression was missing.
 The \lstinline!break! modifier for a variable of a simple type can be applied to the value and/or to specific attributes.
-It is possible to override even if no value is present, either because there was no expression originally or because \lstinline!break! overrides another \lstinline!break!.
+Unless \lstinline!final! was specified, it is possible to override even if no value is present, either because there was no expression originally or because \lstinline!break! overrides another \lstinline!break!.
 
 \begin{nonnormative}
 In a dialog, a tool may hide the keyword \lstinline!break! and show an empty input field, without the overriden modification.
@@ -612,7 +612,7 @@ \subsection{Removing Modifiers -- break}\label{removing-modifiers-break}
 end A;
 
 model B "Initial equation for diameter"
-  extends A( diameter(fixed = false) = break );
+  extends A( final diameter(fixed = false) = break );
   parameter Real square=2;
 initial equation
   //  solving equation below for diameter
@@ -626,7 +626,7 @@ \subsection{Removing Modifiers -- break}\label{removing-modifiers-break}
 end A;
 
 model B "Computing x instead"
-  extends A(x=break);
+  extends A(final x=break);
 algorithm
   x:=0;
   while ...