Allow to create a production build

Right now, we need to run storybook locally via something like npm run storybook. But, it’d be great, if we can build the final HTML and share it anywhere.

So it’ll be something like npm run storybook-build.

Then it’ll create a directory in your project and you can upload those HTML file to anywhere you want and share your stories.

[thani-sh]

Almost done just need to cleanup the code a bit.

[crashuniverse]

@adyz https://storybook.js.org/basics/exporting-storybook/

{
  "scripts": {
    "storybook": "build-storybook -c .storybook -o .out"
  }
}