I am following along to the [Learn Storybook](https://www.learnstorybook.com/design-systems-for-developers/react/en/document/) official tutorial 

I am getting the error `Unexpected default export without title: {"includeStories":[],"parameters":{"docs":{}}}`.

I only have one story in a CreditCard.stories.mdx file in the stories directory: 

```
import { Meta, Story } from '@storybook/addon-docs/blocks';
import { withKnobs, select, boolean } from '@storybook/addon-knobs';

import CreditCard from '../src/CreditCard.js';
<Meta title="Design System|CreditCard" component={CreditCard} />

# Credit card

- This component must use `inputmode="numeric"` in order to bring up the correct keyboard on mobile.

```

config.js file:

```
import { configure } from '@storybook/react';

// automatically import all files ending in *.stories.js
configure(require.context('../stories', true, /\.stories\.(js|mdx)$/), module);

```

addons.js file:

```
import '@storybook/addon-actions/register';
import '@storybook/addon-links/register';
import '@storybook/addon-docs/register';
import '@storybook/addon-knobs/register';

```

presets.js file:

```
module.exports = ['@storybook/addon-docs/react/preset'];

```