Update README.md

Added example and reference

README.md

@@ -2,3 +2,22 @@
 [![Code Climate](https://codeclimate.com/github/touhonoob/RateLimit/badges/gpa.svg)](https://codeclimate.com/github/touhonoob/RateLimit)
 # RateLimit
 Rate Limiting Library With Token Bucket Algorithm
+
+Reference: http://stackoverflow.com/a/668327/670662
+# Example
+````php
+use \Touhonoob\RateLimit\RateLimit;
+use \Touhonoob\RateLimit\Adapter\APC as RateLimitAdapterAPC;
+use \Touhonoob\RateLimit\Adapter\Redis as RateLimitAdapterRedis;
+
+$adapter = new RateLimitAdapterAPC(); // Use APC as Storage
+// $adapter = new RateLimitAdapterRedis(); // Use Redis as Storage
+$rateLimit = new RateLimit("myratelimit", "100", 3600, $adapter); // 100 Requests / Hour
+
+$ip = $_SERVER['REMOTE_ADDR'];
+if ($rateLimit->check($ip)) {
+  echo "passed";
+} else {
+  echo "rate limit exceeded";
+}
+````