Document the return value of `unmount`

[jendrikw]

I can't find anything about that. In react-testing-library it returns void (https://github.com/testing-library/react-testing-library/blob/a2d37ffa09d85b10485f29b79cf7cb4f8ec943db/types/index.d.ts#L45). In this library it returns boolean, but there's no documentation on what that means.

preact-testing-library/types/index.d.ts

Line 12 in 3e5394e

unmount: () => boolean

Edit: It looks like it just calls preactRender which doesn't return anything as per the preact docs, so that makes it even more confusing.

preact-testing-library/src/pure.js

Line 72 in 3e5394e

unmount: () => preactRender(null, container),