Adds method Seq to Supply, refs #2632

Author: JJ

doc/Type/Supply.pod6

@@ -193,6 +193,13 @@ as the C<Supply> emits values. The list will be terminated once the C<Supply> is
 C<done>. If the C<Supply> C<quit>s, then an exception will be thrown once that
 point in the lazy list is reached.
 
+=head2 method Seq
+
+    method Seq(Supply:D:)
+
+Returns a C<Seq> with an iterator containing the values that the C<Supply>
+contains.
+
 =head2 method grab
 
     method grab(Supply:D: &when-done --> Supply:D)