function withPrefix(path) {
    if (path.startsWith(`/`) && !path.startsWith(pathPrefix)) {
      return pathPrefix + path;
    }

    return path;
  }
A Remark Transformer Plugin that adds pathPrefix to
- Relative urls in HTML inside markdown.
- Images referenced from the static directory

Why do we need this?
Because gatsby-transformer-remark doesn't transform HTML
inside markdown. And gatsby-remark-images doesn't transform
images coming from the static folder