I'm a little confused by [the docs about the ready event in hirelings](https://github.com/lmorchard/node-hirelings/blob/master/lib/hirelings.js#L73) - does the event signal that the **pool** is ready, or that the individual worker **process** is ready? The docs and this invocation seem like a pool-wide signal. But the `self.ready();` call in the job exit seems like an individual worker signal?