docs: update composer namespace (#16)

docs/README.md

@@ -5,7 +5,7 @@
 You can install the package via composer:
 
 ```bash
-composer require vyuldashev/laravel-openapi
+composer require tartanlegrand/laravel-openapi
 ```
 
 The service provider will automatically get registered. Or you may manually add the service provider in your config/app.php file: