added readme

README.md

@@ -1,8 +1,53 @@
 # Nazg\HCache
 
+[![Build Status](http://img.shields.io/travis/nazg-hack/hcache/master.svg?style=flat-square)](https://travis-ci.org/nazg-hack/hcache)
+
 ## Installation
 
 ```bash
 $ hhvm -d xdebug.enable=0 -d hhvm.jit=0 -d hhvm.php7.all=1\
  -d hhvm.hack.lang.auto_typecheck=0 $(which composer) require nazg/hcache
 ```
+
+## Usage
+
+*supported apc. memcached, map, void*
+
+### FileSystemCache
+
+```hack
+use Nazg\HCache\Element;
+use Nazg\HCache\Driver\FileSystemCache;
+
+$cache = new FileSystemCache();
+$cache->setDirectory(__DIR__ . '/../storages');
+$cache->save('file', new Element('testing', 0));
+
+$cache->fetch('file');
+$cache->contains('file')
+$cache->flushAll();
+```
+
+### MapCache (memory)
+
+```hack
+use Nazg\HCache\Element;
+use Nazg\HCache\Driver\MapCache;
+
+$cache = new MapCache();
+$cache->save('map', new Element('testing', 0));
+```
+
+### MemcachedCache
+
+```hack
+use Nazg\HCache\Element;
+use Nazg\HCache\Driver\MemcachedCache;
+
+$cache = new MemcachedCache();
+$mc = new \Memcached('mc');
+$mc->addServers([['127.0.0.1', 11211]]);
+$cache->setMemcached($mc);
+$cache->save("qwerty", new Element('testing:cache', 0));
+```
+