Clarifies privacy

Also clarifies example, closes #2420

doc/Type/Routine/WrapHandle.pod6

@@ -1,20 +1,25 @@
 =begin pod
 
-=TITLE class WrapHandle
+=TITLE class Routine::WrapHandle
 
 =SUBTITLE Holds all information needed to unwrap a wrapped routine.
 
 class WrapHandle { ... }
 
-C<WrapHandle> is created and returned by L<wrap|/type/Routine#method_wrap>. Its only use is to unwrap wrapped routines. Either call L<unwrap|/type/Routine#method_unwrap> on a routine object or call the method C<restore> on a C<WrapHandle> object.
+C<WrapHandle> is a I<Rakudo private class> created and returned by
+L<wrap|/type/Routine#method_wrap>. Its only use is to unwrap wrapped routines.
+Either call L<unwrap|/type/Routine#method_unwrap> on a routine object or call
+the method C<restore> on a C<Routine::WrapHandle> object.
 
     sub f() { say 'f was called' }
     my $wrap-handle = &f.wrap({ say 'before'; callsame; say 'after' });
-
-    f;
+    f;                    # OUTPUT: «before␤f was called␤after␤»
     $wrap-handle.restore;
-    f;
-    # OUTPUT: «before␤f was called␤after␤f was called␤»
+    f;                    # OUTPUT: «f was called␤»
+
+As such private class, it may suffer any kind of changes without prior notice.
+It is only mentioned here since it is visible by the user who checks the return
+type of the C<Routine.wrap> method.
 
 =head1 Methods