Here is my directory structure ``` SUMMARY.md dir1/ content.md picture.png ``` There is a link to `picture.png` in `content.md`: ```  ``` After `mdbook build` these files contain `<img src="./picture.png" alt="my picture">` * `book/index.html` * `book/print.html` * `book/dir1/content.html` This is correct for `content.html` but not for `index.html` and `print.html`. The image is not shown.