Adding an example that clarifies how subs are accessed

... from outer scopes. This closes #2220

doc/Type/Sub.pod6

@@ -46,7 +46,22 @@ X<|my (Sub)>X<|our (Sub)>
 Subs can be nested and scoped with C<my> and C<our>, whereby C<my> is the
 default. A sub declared with C<my> can not be reached from any outer scope. An
 C<our> scoped sub will not redefine a sub of the same name in the outer scope.
-Any sub can be accessed via a closure from any outer scope.
+Any sub can be accessed via a closure from any outer scope. For instance, in
+this example
+
+    sub can-be-seener( $whatever ) {
+      my sub can-be-seen ( $objection ) {
+        return $whatever but $objection;
+      }
+      return &can-be-seen
+    }
+
+    my $objectioner = can-be-seener( "Really?");
+    say $objectioner(42).Int; # OUTPUT: «42␤»
+
+C<$objectioner> will contain the C<can-be-seen> subroutine, even if it has been
+declared in another scope; calling it with C<42> will return C<"Really?"> with
+the number 42 mixed in, as shown in the last sentence.
 
 =head1 Traits
 X<|trait_mod (declarator)>