Repo's About Website URL

## Issue
The current `About` section has a broken link to the website [design.carbonplan.org](https://design.carbonplan.org/).

<img width="1390" height="339" alt="Image" src="https://github.com/user-attachments/assets/535c8ae2-ea26-433d-a0e9-2f704c7070c2" />

## Fix
I'm guessing link to [carbonplan.org/design](https://carbonplan.org/design)?