Merge pull request #227 from jordanwalsh23/master

added whispir.io to the list of reference sites

Author: lord

README.md

@@ -83,6 +83,7 @@ Examples of Slate in the Wild
 * [Paracel API Reference](http://paracel.io/docs/api_reference.html)
 * [Switch Payments Documentation](http://switchpayments.com/docs/) & [API](http://switchpayments.com/developers/)
 * [Coinbase API Reference](https://developers.coinbase.com/api)
+* [Whispir.io API](https://whispir.github.io/api)
 
 (Feel free to add your site to this list in a pull request!)