Add Helsinki (#2271)

README.md

@@ -754,6 +754,7 @@ API | Description | Auth | HTTPS | CORS |
 | [BusinessUSA](https://business.usa.gov/developer) | Authoritative information on U.S. programs, events, services and more | `apiKey` | Yes | Unknown |
 | [Census.gov](https://www.census.gov/data/developers/data-sets.html) | The US Census Bureau provides various APIs and data sets on demographics and businesses | No | Yes | Unknown |
 | [City, Gdańsk](https://ckan.multimediagdansk.pl/en) | Gdańsk (PL) City Open Data | No | Yes | Unknown |
+| [City, Helsinki](https://hri.fi/en_gb/) | Helsinki(FI) City Open Data | No | Yes | Unknown |
 | [City, Nantes Opendata](https://data.nantesmetropole.fr/pages/home/) | Nantes(FR) City Open Data | `apiKey` | Yes | Unknown |
 | [City, New York Opendata](https://opendata.cityofnewyork.us/) | New York (US) City Open Data | No | Yes | Unknown |
 | [City, Prague Opendata](http://opendata.praha.eu/en) | Prague(CZ) City Open Data | No | No | Unknown |