Add Graph Countries API (#1229)

README.md

@@ -455,6 +455,7 @@ API | Description | Auth | HTTPS | CORS |
 | [geoPlugin](https://www.geoplugin.com) | IP geolocation and currency conversion | No | Yes | Yes |
 | [Google Earth Engine](https://developers.google.com/earth-engine/) | A cloud-based platform for planetary-scale environmental data analysis | `apiKey` | Yes | Unknown |
 | [Google Maps](https://developers.google.com/maps/) | Create/customize digital maps based on Google Maps data | `apiKey` | Yes | Unknown |
+| [Graph Countries](https://github.com/lennertVanSever/graphcountries) | Country-related data like currencies, languages, flags, regions+subregions and bordering countries | No | Yes | Unknown |
 | [HelloSalut](https://www.fourtonfish.com/hellosalut/hello/) | Get hello translation following user language | No | Yes | Unknown |
 | [HERE Maps](https://developer.here.com) | Create/customize digital maps based on HERE Maps data | `apiKey` | Yes | Unknown |
 | [IP 2 Country](https://ip2country.info) | Map an IP to a country | No | Yes | Unknown |