Renders a tray.
Input:
{% tray "footer" %}
Includes trays/footer.plate.
Note that there must be a Tray with this name present in the 'Trays' tab under the Content Types dashboard.
You can access the tray object inside the theme file by calling the name of the tray as a variable, in this case footer. Trays behave the same like sections, so your tray theme file would look like this:
{% content_for footer %}
{% render_content %}
{% endcontent_for %}