Bring Order to Storybook

[mrm1st3r]

The sections in our Storybook are currently ordered only alphabetically, which isn't a whole lot helpful.
Storybook allows to define a custom sort-order.

For now, the order should be:

• Introduction
• Foundation/Design-Tokens
• Components (not yet on main branch)

Currently, the "foundation" and "design-tokens" sections aren't clearly distinguishable and might be joined.
Which of the two names to keep is up for discussion in the team.