Fix return type of subscribe function

[skuteli]

The example in Readme calls for using unsubscribe in useEffect like this: return ()=>unsubscribe() This raises an error as the return type of api.whatever.subscribe(...) is void. In fact proper value is returned, but the example wraps unnecessarily and type definition is void instead of ()=>void. Also fixed Readme because this arrow function is not needed. Could be even

useEffect(() => api.velocity.subscribe((v) => (velocity.current = v)), [])

instead of

useEffect(() => {
  const unsubscribe = api.velocity.subscribe((v) => (velocity.current = v))
  return () => unsubscribe()
}, [])

but I don't have enough courage to change that much ;)

[bjornstar]

Thanks, I wonder if there is a rule in typescript that prevents this type of error.