Add some documentation about the project

Author: henriquemoody

README.md

@@ -8,3 +8,39 @@
 [![License](https://img.shields.io/packagist/l/respect/stringifier.svg?style=flat-square)](https://packagist.org/packages/respect/stringifier)
 
 Converts any PHP value into a string.
+
+## Installation
+
+Package is available on [Packagist](https://packagist.org/packages/respect/stringifier), you can install it
+using [Composer](http://getcomposer.org).
+
+```bash
+composer require respect/stringifier
+```
+
+This library requires PHP >= 7.1.
+
+## Feature Guide
+
+Below a quick guide of how to use the library.
+
+### Namespace import
+
+Respect\Stringifier is namespaced, and you can make your life easier by importing
+a single function into your context:
+
+```php
+use function Respect\Stringifier\stringify;
+```
+
+Stringifier was built using objects, the `stringify()` is a easy way to use it.
+
+### Usage
+
+Simply use the function to convert any value you want to:
+
+```php
+echo stringify($value);
+```
+
+To see more examples of how to use the library check the [integration tests](tests/integration).