Cross-ref docs about hooks coming to RFF V5 (#45)

* Cross-ref docs about hooks coming to RFF V5 

Hooks are coming to React Final Form!  final-form/react-final-form#467

This PR adds a paragraph to the readme of `react-final-form-hooks` to let people know that there's also hooks work going on in the main RFF codebase. Given that Googling "react final form hooks" will end up on this page for the forseeable future, it's useful to warn folks who're looking to use more hooks that they will soon have another option besides `react-final-form-hooks`.

* Fixed typos

Author: justingrant

README.md

@@ -39,6 +39,8 @@ yarn add react-final-form-hooks final-form
 
 If performance is your goal, you are recommended to use [🏁 React Final Form](https://github.com/final-form/react-final-form). Also, that library does many other things for you, like managing checkbox and radio buttons properly. RFFHooks leaves all of that work to you. By default, 🏁 React Final Form Hooks subscribes to _all_ changes, but if you want to fine tune your form, you may specify only the form state that you care about for rendering your gorgeous UI.
 
+If you like the the developer experience of using React hooks but need the full featureset of 🏁React Final Form, then help is on the way: starting with v5.0, 🏁 React Final Form will export `useField` and `useFormState` hooks that can simplify field handling. These new hooks don't cover the entire surface area of 🏁 React Final Form because some features still require render props, but they will provide a more flexible and feature-rich solution compared to the bare-bones approach of `react-final-form-hooks`. To track this work before V5 is released, you can follow the [work-in-progress PR](https://github.com/final-form/react-final-form/pull/467).
+
 Here's what it looks like in your code:
 
 ```jsx