Update README.md

README.md

-# php-device-cookies
+# PHP device cookies
 Implementation of Device Cookies in PHP
+
+Heavily based on [Device cookie example](https://github.com/Rundiz/device-cookies-example), which is an implementation of [Device cookies](https://owasp.org/www-community/Slow_Down_Online_Guessing_Attacks_with_Device_Cookies) described by OWASP.
+
+## Installation
+
+```
+composer install php-device-cookies
+```
+
+## Usage
+
+Use the provided `DeviceCookies` class.