Adds @zoffix's example to sink context

Author: JJ

doc/Language/contexts.pod6

@@ -19,6 +19,19 @@ You can force that sink context on L<Iterator>s, by using the L<C<sink-all>|/rou
 
 In general, blocks will warn if evaluated in sink context; however, L<gather/take blocks|/language/control#Flow%29_gather_take> are explicitly evaluated in sink context, with values returned explicitly using C<take>.
 
+In sink context, an object will call its `sink` method if present:
+
+=begin code
+sub foo {
+    return [<a b c>] does role {
+        method sink { say "sink called" }
+    }
+}
+foo
+# OUTPUT: sink called
+=end code
+
+
 =head1 Number X<|number context>
 
 This context, and probably all of them except sink above, are I<conversion> or I<interpretation> contexts in the sense that they take an untyped or typed variable and duck-type it to whatever is needed to perform the operation. In some cases that will imply a conversion (from L<Str> to L<Int>, for instance); in other cases simply an interpretation (L<IntStr> will be interpreted as L<Int> or as L<Str>).