Include markdown files

[unlikenesses]

I'm using some pre-existing Twig templates in a new Laravel 8 app. These contain lines like:

{% filter markdown %}{% include 'foo/bar.md' %}{% endfilter %}

This produces the error:

Template "foo/bar.md" is not defined in "baz.twig" at line 8.

How can I include markdown files with TwigBridge?