Description
Is your feature request related to a problem? Please describe.
I am using Front Matter with the Gatsby framework and MDX files. My folder structure looks basically identical to the "Page and leaf bundles" example (except I use MDX files). When I add an image located in the same folder as the the index.mdx file, Front Matter always adds the absolute path to the image (/content/posts/leaf-bundle/image1.jpg) instead of the much shorter relative path (./image1.jpg). However, Gatsby MDX does not seem to support absolute image paths out of the box, so it fails creating the post when it encounters the image url.
Describe the solution you'd like
I would love a setting that forces relative paths when adding images through Front Matter. In the example above, the path would then be only the image's file name and not the full absolute path. It should also apply to sibling leaf-nodes (../leaf-bundle-2/image2.jpg). This would make resolving (image) files in the same directory much easier in Gatsby, but I am sure this also applies to other frameworks as well.
Describe alternatives you've considered
The alternative would be to find a Gatsby workaround for this, which I could not find yet unfortunately.