Update repo url to correct one

[nicholas-l]

The url points to the old outdated repo and I am hoping that yarn uses this for the URL column when running yarn outdated :)

Launch Checklist

• briefly describe the changes in this PR
• write tests for all new functionality
• document any changes to public APIs
• post benchmark scores
• manually test the debug page
• tagged @mapbox/studio and/or @mapbox/maps-design if this PR includes style spec changes

[mourner]

Should we change that to point to the specific folder? At least that's what Babel uses: https://github.com/babel/babel/blob/master/packages/babel-highlight/package.json#L11
(Although on the other hand, e.g. React packages point to the same facebook/react repo, so no defined standard here)

[nicholas-l]

I would leave it as the repository not the folder as if the packages gets moved or the main branch changes, the url may not get updated, leaving a bad user experience (404 page).