chore(readme): documentation

README.md

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+
+WP Basic Requirements
+=====================
+
 Wp-basic-requirements is a simple library for WordPress plugins to check if the environment meets the requirements
 and if the requirements are not met shows proper notice to user.
 
@@ -9,4 +19,45 @@ Requirements may be:
 - Minimal WooCommerce version
 - Required PHP module
 - Required PHP setting
-- OpenSSL version
\ No newline at end of file
+- OpenSSL version
+
+## Requirements
+
+PHP 5.2 or later.
+
+## Installation via Composer
+
+In order to install the bindings via [Composer](http://getcomposer.org/) run the following command:
+
+```bash
+composer require wpdesk/wp-basic-requirements
+```
+
+## Example usage
+
+Use this code in main WordPress plugin file: 
+
+```php
+<?php
+
+$requirements_checker = ( new WPDesk_Basic_Requirement_Checker_Factory )->create_from_requirement_array(
+    __FILE__,
+    'Example plugin name',
+    [	
+        'php'     => '7.0',
+        'wp'      => '6.0',
+        'plugins' => [
+            [
+                'name'      => 'woocommerce/woocommerce.php',
+                'nice_name' => 'WooCommerce',
+            ],
+        ],
+    ]
+);
+
+if ( $requirements_checker->are_requirements_met() ) {
+    // plugin stuff goes here
+} else {
+    $requirements_checker->render_notices();
+}
+```