Adds declaration of junctions, refs #2703

Author: JJ

doc/Type/Junction.pod6

@@ -28,6 +28,11 @@ C<none>.
 
 =end table
 
+By default, C<any> Junctions are defined. In order to create the other types of
+junctions, you use the string that represents the type followed by any object,
+or else call L<C<.all>|/routine/all>, L<C<.none>|/routine/none> or
+L<C<.one>|/routine/one> on the object.
+
 Autothreading happens when a junction is bound to a parameter of a code object
 that doesn't accept values of type C<Junction>. Instead of producing an error,
 the signature binding is repeated for each value of the junction.
@@ -256,4 +261,4 @@ On the other hand, the versions of C<~> that use a string as one argument will j
 
 =end pod
 
-# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6