The content related to the footer is stored in a specific content type (Layout).
ref: https://jira.ez.no/browse/COM-19889

Technical

• Create a controller for fetching the specific content item (example: https://github.com/ezmarket/ezplatform_ezstudio_site/blob/master/src/AppBundle/Controller/SiteController.php#L49)
• Create a template footer.html.twig