Automatically generate JavaScript API Reference from JSDoc

[36degrees]

What

Once we're happy with the format and location, we should work out how to automatically generate the JavaScript API Reference from JSDoc at build time, rather than hand-writing it and manually keeping it in sync with the JSDoc in the code.

Why

Automatically generating the JavaScript API Reference from the JSDoc avoids duplication of effort and ensures that the API reference will always be in sync with the code in the most recently published release.

Who needs to know about this

Developers, tech writer

Done when

• The JavasScript API Reference is automatically generated from the inline JSDoc in our components

[36degrees]

https://github.com/jsdoc2md/jsdoc-to-markdown looks like it might be useful for this

[stevenjmesser]

@colinrotherham Did we add JSDoc to Frontend meaning this can now be closed?

[colinrotherham]

@stevenjmesser It's half done! This issue represents step 2

We're currently using TypeDoc to render our JSDoc documentation
https://govuk-frontend-review.herokuapp.com/docs/javascript/

But similar to the Sass API reference we may want to generate a branded public facing JavaScript API reference too

[36degrees]

API Extractor looks like it might be useful for this.

[domoscargin]

When we do this, we should also review our code comments/documentation to ensure the generated documentation is clear and helpful.

We noted some improvements here: #555