markdown: support displaying images in Stash repo

README.md supports image URLs, but it seems only external URLs work. AFAICS, anyway.

If the image is in the same git repo and you use a relative name, Stash translates the image name to something like /projects/PROJECT/repos/repo-name/browse/doc/image.png, but doesn't find it when browsing the repository. This makes it impossible to create README.md files with images in a Stash git repo, unless there is some way to do it that I can't find in the docs.

But I don't want to use an absolute path because the same README then won't work when converted to HTML using the markdown program itself (which works fine with relative image names, btw).

Any ideas?