Add checkbox on sample form in README.

This adds the motivation on using the library, with the pitfalls on
using other form libraries.

Handle selects, as well as file uploads.

For republishing.

We have added a more meaningful code sample in the README file.

Also, the publishing will happen on multiple registries, just like
`@theoryofnekomata/react-musical-keyboard`

Note on installation.

Include short details on using the library.

This commit adds Cypress for testing the library against a real DOM.

Add files from TSDX.