MDX, the powerful authoring format that lets you write JSX content inside of your markdown content, is an amazing tool to deliver interactive experiences to your readers. 

There are a few problems that you can encounter when using Gatsby and MDX, however. For example, if you want to use Gatsby image preprocessing capabilities with a featured image from your `frontmatter`, you need to tap into the Gatsby build system through the `gatsby-node.js` file to retrieve the image and create the corresponding Node. But what if you want to use the filesystem routing API from Gatsby instead?
