When referencing image links to a root path the validation fails (while mkdocs itself suceeds for the image).

Given this example: (Root referencing required for common language shared between multilingual folders)

![test](/common/image1.png)

This will succeed validation for the image itself in mkdocs build, but when used together with the glightbox plugin which generates an link for the image to zoom in the validation of the link will fail with htmlproofer (404 error).

<a href="/common/image1.png"><img ......></a>

HTML proofer should validate local root links against the site folder.