Links the other section on TWEAK

doc/Language/classtut.pod6

@@ -118,7 +118,9 @@ say Str-with-ID.new(string => 'Second').ID; # OUTPUT: «1»
 
 In this case, we need to compute C<$.ID> from the value of a counter that is a
 class variable, C<$.counter>, thus we simply assign a value to it and increment
-the counter at the same time.
+the counter at the same time. Please check also
+L<this section on C<TWEAK> in the OO document|/language/objects#index-entry-TWEAK>
+for the mechanics of object construction.
 
 =head1 Starting with class