Draft: Add design system philosophy guidance page
Relates to issue #2019
This MR was created by Duo in Session 1225455
Changes
- Add new guidance page explaining the philosophy and mental model behind using the design system.
- Help designers understand how to incorporate the system into their daily workflows and decision-making.
- Define fundamental ideas about design system usage and responsibilities.
- Reorders some navigation to keep this new content as a sibling to principles.
Edited by Jeremy Elder