Postcodes.io Added

Postcode & Geolocation API for the UK

README.md

@@ -79,6 +79,7 @@ A collective list of JSON APIs for use in web development.
 | API | Description | OAuth |Link |
 |---|---|---|---|
 | OpenCage | Forward and reverse geocoding using open data | No | [Go!](https://geocoder.opencagedata.com) |
+| Postcodes.io | Postcode & Geolocation API for the UK | No | [Go!](https://http://postcodes.io/) |
 
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