We have a very interesting page called Design Principles: https://github.com/flutter/website/blob/master/design-principles.md

Which seems to be mostly about principles for Flutter and Flutter's framework design principles. The audience for this doc seems to be people wanting to contribute to and with the project.

To reduce confusion, we can consider renaming this doc to "Project Principles" or similar.

"Design" could be confused with "app design" or "app architecture design".