pandemicRC Demo para HackTechCovid19 Librerias externas y APIs Mapas gratuitos leafletjs.com Casos de covid covid-19-mexico-sigsamx.hub.arcgis.com/datasets/casos-covidmapa JSON API https://services.arcgis.com/CT0bYvH48f1TEH2t/arcgis/rest/services/Covid19/FeatureServer/0/query?where=1%3D1&outFields=*&outSR=4326&f=json