add example

Author: carlosmiei

examples/orders_testnet.php

@@ -0,0 +1,14 @@
+<?php
+
+require '../php-binance-api.php';
+
+// @see home_directory_config.php
+// use config from ~/.confg/jaggedsoft/php-binance-api.json
+$api = new Binance\API("<testnet api key>","<testnet secret>", true);
+
+// Place a LIMIT order using the testnet
+$quantity = 1000;
+$price = 0.0005;
+$order = $api->buy("BNBBTC", $quantity, $price);
+print_r($order);
+