The design-demo example was removed in the commit f0bfa87. The submodule was then added back by @wash2 in the commit f9af93c. The commit was about was about updating iced so I suspect it got added back by accident.
In issue #374 @mmstick said about it: "The project is not maintained right now. It should be removed."
I have removed the design-demo example again along with some other leftover parts. I also fixed the examples README.md file.
This closes issue #374
