[FEATURE] Add example of adding durable object

[Jbithell]

Is your feature request related to a problem?

@vicb added an example of adding a custom worker in #591, but it is unclear how to export workers from the custom worker without either specifying a script_name and running in to Error: Cannot access ExampleDurableObject#sayHello as Durable Object RPC is not yet supported between multiple wrangler dev sessions. or not specifying one and getting workerd/jsg/util.c++:320: error: e = workerd/io/worker.c++:3487: failed: broken.ignored; no such actor class; c = ExampleDurableObject stack: 1025bc777 10205bd7b 10205b833 10205b18b 102058df3 102925a38 102925e9f 10204731c 102aac004 102aaaed0 10204e1ac 1028ce3b8; sentryErrorContext = jsgInternalError; wdErrId = umnd8uh3o319ejl6659trha9

Describe the solution you'd like

Please could a simple working example be provided of exporting a durable object from ./custom-worker.ts

Describe alternatives you've considered

Running two wrangler instances

@opennextjs/cloudflare version

1.1.0

Additional context

No response

Before submitting

• I have checked that there isn't already a similar feature request
• This is a single feature (not multiple features in one request)

[Dosbodoke]

Would love to see some examples on This. It's quite funny that I found this thread with 1 hour posted, but just deployed the starter example and am currently struggling with setting up a WebSocket Hibernation Durable Object.