update readme

Author: cesargb

README.md

@@ -7,6 +7,14 @@ This class permit log rotating with diferetne processor.
 [![tests](https://github.com/cesargb/php-log-rotation/workflows/tests/badge.svg)](https://github.com/cesargb/php-log-rotation/actions)
 [![Latest Version on Packagist](https://img.shields.io/packagist/v/cesargb/php-log-rotation.svg?style=flat-square&color=brightgreen)](https://packagist.org/packages/cesargb/php-log-rotation)
 
+## Installation
+
+You can install this package via composer using:
+
+```bash
+composer require cesargb/php-log-rotation
+```
+
 ## Usage
 
 This is an example: