Mapzen Search requires apiKey

Mapzen services require api key, which developers can get at: https://mapzen.com/developers/

README.md

@@ -272,7 +272,7 @@ API | Description | Auth | HTTPS | Link |
 | IP Address Details| Find geolocation with ip address | No | Yes | [Go!](https://ipinfo.io/) |
 | IP Vigilante | Free IP Geolocation API | No | Yes | [Go!](https://www.ipvigilante.com/) |
 | Mapbox | Create/customize beautiful digital maps | `apiKey` | Yes | [Go!](https://www.mapbox.com/developers/) |
-| Mapzen Search | Open Source & Open Data Global Geocoding Service | No | Yes | [Go!](https://mapzen.com/products/search/) |
+| Mapzen Search | Open Source & Open Data Global Geocoding Service | `apiKey` | Yes | [Go!](https://mapzen.com/products/search/) |
 | Mexico | Mexico RESTful zip codes API | No | Yes | [Go!](https://github.com/IcaliaLabs/sepomex) |
 | One Map 2.0, Singapore| Singapore Land Authority REST API services for Singapore addresses  | `apiKey` | Yes | [Go!](https://docs.onemap.sg/) |
 | OpenCage | Forward and reverse geocoding using open data | No | Yes | [Go!](https://geocoder.opencagedata.com) |