rename service.options.methods to service.options.exposeMethods

[fratzinger]

Looking at this:

.use('my-service', new MyService(), {
  // Pass all methods you want to expose
  methods: ['get', 'myCustomMethod']
})

I have two problems with the key 'methods' as being used here:

• It's totally unclear, that it's meant to be used for exposition only. I would expect methods to be meant for more than that. Something like exposeMethods would be much better.
• This is more theoretically: The key 'methods' could be a much better fit for other use cases in the future (imagine inference, or something else). Leave this one for better use cases.

I know it's a breaking change and I know we shouldn't change this 4 days before the final release. Maybe we can elaborate such changes for v6 with a much smaller release cycle.