Add Metadapi Zip Code API

Created entry for the zip code data api from Metadapi

README.md

@@ -1001,6 +1001,7 @@ API | Description | Auth | HTTPS | CORS |
 | [ViaCep](https://viacep.com.br) | Brazil RESTful zip codes API | No | Yes | Unknown |
 | [What3Words](https://what3words.com) | Three words as rememberable and unique coordinates worldwide | `apiKey` | Yes | Unknown |
 | [Yandex.Maps Geocoder](https://yandex.com/dev/maps/geocoder) | Use geocoding to get an object's coordinates from its address | `apiKey` | Yes | Unknown |
+| [Zip Code Data](https://www.metadapi.com/API-Products/Zip-Code-API) | US enhanced zip code data, PO Box validations, distance between zip codes, radius and more | `apiKey` | Yes | Unknown |
 | [ZipCodeAPI](https://www.zipcodeapi.com) | US zip code distance, radius and location API | `apiKey` | Yes | Unknown |
 | [Zippopotam.us](http://www.zippopotam.us) | Get information about place such as country, city, state, etc | No | No | Unknown |
 | [Ziptastic](https://ziptasticapi.com/) | Get the country, state, and city of any US zip-code | No | Yes | Unknown |