Update README

Author: Ivan Vasilkov

README.md

@@ -3,9 +3,24 @@
 Simple translation and pluralization php library based on files. 
 
 Overview:
+- [Requirements](#requirements) 
+- [Installation](#installation) 
 - [Localization](#localization) 
 - [Pluralization](#pluralization) 
 
+## Requirements
+
+* PHP 8.1+
+* PDO Extension with desired database drivers
+
+## Installation
+
+Install package via composer:
+
+```shell
+$ composer require compositephp/localization
+```
+
 ## Localization
 
 First, you need to create new class and extend from `Composite\Localization\AbstractLocalization`