Add link to 'Scalar' class in containers documentation.

Author: fluca1978

doc/Language/containers.pod6

@@ -28,7 +28,7 @@ container>.
 
 =head1 Scalar containers
 
-Although objects of type C<Scalar> are everywhere in Perl 6, you rarely
+Although objects of type L<C<Scalar>|/type/Scalar> are everywhere in Perl 6, you rarely
 see them directly as objects, because most operations
 I<decontainerize>, which means they act on the C<Scalar> container's
 contents instead of the container itself.