Add Coinlib.io (#879)

* Add Coinlib.io

* Add link to API doc

README.md

@@ -183,6 +183,7 @@ API | Description | Auth | HTTPS | CORS |
 | [CoinGecko](http://www.coingecko.com/api) | Cryptocurrency Price, Market, and Developer/Social Data | No | Yes | Yes |
 | [Coinigy](https://coinigy.docs.apiary.io) | Interacting with Coinigy Accounts and Exchange Directly | `apiKey` | Yes | Unknown |
 | [CoinLayer](https://coinlayer.com) | Real-time Crypto Currency Exchange Rates | `apiKey` | Yes | Unknown |
+| [Coinlib](https://coinlib.io/apidocs) | Crypto Currency Prices | `apiKey` | Yes | Unknown |
 | [Coinlore](https://www.coinlore.com/cryptocurrency-data-api) | Cryptocurrencies prices, volume and more | No | Yes | Unknown |
 | [CoinMarketCap](https://coinmarketcap.com/api/) | Cryptocurrencies Prices | `apiKey` | Yes | Unknown |
 | [Coinpaprika](https://api.coinpaprika.com) | Cryptocurrencies prices, volume and more | No | Yes | Yes |