update section on class bodies for extends final

Author: ginsbach

docs/codeql/ql-language-reference/types.rst

@@ -135,8 +135,9 @@ The body of a class can contain:
   -  Any number of :ref:`field <fields>` declarations. 
 
 When you define a class, that class also inherits all non-:ref:`private` member predicates and
-fields from its supertypes. You can :ref:`override <overriding-member-predicates>` those 
-predicates and fields to give them a more specific definition.
+fields from its supertypes.
+You can :ref:`override <overriding-member-predicates>` or :ref:`shadow <final-extensions>` those
+predicates and fields (depending on whether they are final) to give them a more specific definition.
 
 .. _characteristic-predicates: