In order to make the storybook visible to everyone. Some changes
had to be made to make index.scss compiled with the rest of the
codebase, it had to be imported from preview.js, not directly from
preview.html.
Previously the docs order was defined by the default behavior of
Storybook: discovery order. But, in our situation we want the
"Getting Started" part to appear above "Components", and "Doc"
above any other stories. So we needed to create a custom sort callback.
In order to make this storySort callback to be taken into account by Storybook
it was needed to rename the file to preview.js. Strange but .. meh.
