fix remote execution syntax in docs

[ghost]

The docs show various examples of remote execution such as

        def id = remote {
            def person = new Person(name: "Me")
            person.save()
            person.id
        }

But as far as I can tell this doesn't work and remote.exec should be used instead, e.g.

        def id = remote.exec {
            def person = new Person(name: "Me")
            person.save()
            person.id
        }