Updated readme

README.md

@@ -1,2 +1,30 @@
 # php-holidayapi
 Official PHP library for [Holiday API](https://holidayapi.com)
+
+## Installation
+
+```shell
+composer require "joshtronic/php-holidayapi:dev-master"
+```
+
+## Usage
+
+```php
+$hapi = new HolidayAPI\v1('_YOUR_API_KEY_');
+
+$parameters = array(
+  // Required
+  'country' => 'US',
+  'year'    => 2016,
+  // Optional
+  // 'month'   => 7,
+  // 'day'     => 4,
+  // 'previous' => true,
+  // 'upcoming' => true,
+  // 'public'   => true,
+  // 'pretty'   => true,
+);
+
+$response = $hapi->holidays($parameters);
+```
+