How to defined index page content with extra.ford usage

When using `extra.ford` in `fpm.toml` where/how do I define the contents of the main index page for the docs? What seems to be happening is that it's including the `fpm.toml` contents there, which isn't what I want. Normally I just want it to be the project README.md file, which I have done with the `ford.md` way by using `{!README.md!}`.