docs: update info on valid JSON
docs: update info on valid JSON

albertcrowley/project-open-data-dashboard,dhootha/project-open-data-dashboard,dhootha/project-open-data-dashboard,mchelen/project-open-data-dashboard,dhootha/project-open-data-dashboard,mchelen/project-open-data-dashboard,mchelen/project-open-data-dashboard,albertcrowley/project-open-data-dashboard,albertcrowley/project-open-data-dashboard