Missing docs for `types.lazy`

[coolsoftwaretyler]

Bug report

• [x] I've checked documentation and searched for existing issues and discussions
• [x] I've made sure my project is based on the latest MST version
• [ ] Fork this code sandbox or another minimal reproduction.

Describe the expected behavior

We should have documentation for types.lazy, introduced in https://github.com/mobxjs/mobx-state-tree/pull/1722, but we neglected to enforce that.

Describe the observed behavior

There is no documentation. We'll reach out to the original author to see if they want to add it. If we don't hear back soon, someone on core team will handle it or find a volunteer to do so.

[coolsoftwaretyler]

Hey @clgeoio - it's probably been a while since you heard from us at MobX-State-Tree, but we realized that your types.lazy (which is awesome by the way) never got documented.

Do you have any interest in writing those docs for us? Let me know either way, thank you!

[jamonholmgren]

There is this: https://github.com/mobxjs/mobx-state-tree/blob/master/docs/API/index.md#lazy

I can't seem to find it on the website, though. Maybe just needs to be deployed?

Also needs a usage example.