chore(app): init design doc

[Chandan-CV]

Right now we have no way to keep track of the UI/UX design of the app. Hence creating a markdown file containing:

1. The current figma project link
2. design principles used in the design
3. important pointers
4. contributors
5. recent changes (should also be able to track with a descriptive commit history)

[abhigyantrips]

I think we can do this by having issues laid out under a project, and a main Figma link in the contribution docs.

[abhigyantrips]

This can be crudely arranged internally for now, a public version is lower priority.