The 3.0k bundle size claim is false

### Are you submitting a **bug report** or a **feature request**?

I'm submitting a comment about the bundle size claim in your README.

### What is the current behavior?

The README states that your bundle size is **3.0k gzipped**. That is false because this library simply will not working without including `final-form` as well. Therefore, your bundle size is more like **8.1k** gzipped at this time. See [1](https://bundlephobia.com/result?p=react-final-form@6.3.0) and [2](https://bundlephobia.com/result?p=final-form@4.18.5).

Not only that, to get all of the features of a well-known competitor that this is probably being compared to (Formik) you must include `react-final-form-arrays` [3](https://bundlephobia.com/result?p=react-final-form-arrays@3.1.1) which adds another **1.3k** for a total of **9.4k** gzipped.

So, the claim of a **3.0k gzipped** bundle size seems unfair to devs who are comparing these libraries.

### What is the expected behavior?

That one can actually get all of the advertised functionality while only adding **3.0k** to their gzipped bundle size. It's impossible.

### Sandbox Link

None.

### What's your environment?

Latest.

### Other information

- [1] https://bundlephobia.com/result?p=react-final-form@6.3.0
- [2] https://bundlephobia.com/result?p=final-form@4.18.5
- [3] https://bundlephobia.com/result?p=react-final-form-arrays@3.1.1