Add link to designsystemet

[Albertlarsen]

Description

Added link and description for designsystemet.no in introduction in altinn storybook.

Related Issue(s)

• Fixes: https://github.com/digdir/designsystem/issues/10

Verification

• [ ] Your code builds clean without any errors or warnings
• [ ] Manual testing done (required)
• [ ] Relevant automated test added (if you find this hard, leave it and we'll help out)
• [ ] All tests run green

Documentation

• [ ] User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (4cac5ad) 95.51% compared to head (0cf33a3) 95.51%. Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #336 +/- ## ======================================= Coverage 95.51% 95.51% ======================================= Files 29 29 Lines 357 357 Branches 95 95 ======================================= Hits 341 341 Misses 14 14 Partials 2 2 ```

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