Minimal Repoduction of mdBook's Broken Landing Page Links Bug
Run ./break-the-links.sh
and then open http://0.0.0.0:3000/book/ in the browser.
You will notice that clicking on the 'another page' link gives a 404 error.
Not a problem when /index.md exists.
# Summary
[Landing Page](./landing/page.md)
- [Another Page](./another-page.md)
- [Not the start, but the root.](./index.md)In this case,
http://0.0.0.0:3000/book/ takes you to ./index.md.