Add example of improved option() capability.

[krlawrence]

Release 3.4.3 added the ability for option steps used with a choose step to include traversals so constructs like the one below are now possible.

g.V().hasLabel('airport').
      groupCount().
        by(__.choose(__.values('elev')).
                     option(gt(5000),__.constant('high')).
                     option(gt(3000),__.constant('medium')).
                     option(Pick.none,__.constant('low'))) 

Also show to do it before would have taken something like

res = ( g.V().hasLabel('airport').
              groupCount().
                by(__.choose(__.values('elev').is_(gt(5000)),
                             __.constant('high'),
                             __.choose(__.values('elev').is_(gt(3000)),
                                       __.constant('medium'),
                                       __.constant('low')))).
              order(Scope.local).by(Column.values).
              next() )

As part of this also document the Pick enum. org.apache.tinkerpop.gremlin.process.traversal.step.TraversalOptionParent.Pick

Maybe also show something like this as the old option usage

gremlin> g.V().hasLabel('airport').
......1>       has('region','US-TX').fold().
......2>       choose(count(local)).
......3>         option(1,constant('one')).
......4>         option(0,constant('none')).
......5>         option(none,constant('neither one or zero'))
==>neither one or zero
gremlin> g.V().hasLabel('airport').
......1>       has('code','AUS').fold().
......2>       choose(count(local)).
......3>         option(1,constant('one')).
......4>         option(0,constant('none')).
......5>         option(none,constant('neither one or zero'))
==>one
gremlin> g.V().hasLabel('airport').
......1>       has('code','XYZ').fold().
......2>       choose(count(local)).
......3>         option(1,constant('one')).
......4>         option(0,constant('none')).
......5>         option(none,constant('neither one or zero'))
==>none       

As part of this update the Pick enum needs to be added to the list of enum tables