Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -1,20 +1,17 @@
 Contributing
------
+------------
 
-All code is Symfony2 Code formatted, so every pull request must validate phpcs
-standards. You should read 
-[Symfony2 coding standards](http://symfony.com/doc/current/contributing/code/standards.html)
-and install [this](https://github.com/opensky/Symfony2-coding-standard) 
-CodeSniffer to check all code is validated.
+This project follows some standards. If you want to collaborate, please ensure
+that your code fulfills these standards before any Pull Request.
 
-There is also a policy for contributing to this project. All pull request must
-be all explained step by step, to make us more understandable and easier to
-merge pull request. All new features must be tested with PHPUnit.
+``` bash
+composer.phar update
+bin/php-cs-fixer fix
+bin/php-formatter formatter:use:sort src/
+bin/php-formatter formatter:header:fix src/
+```
 
-If you'd like to contribute, please read the [Contributing Code][1] part of the
-documentation. If you're submitting a pull request, please follow the guidelines
-in the [Submitting a Patch][2] section and use the [Pull Request Template][3].
-
-[1]: http://symfony.com/doc/current/contributing/code/index.html
-[2]: http://symfony.com/doc/current/contributing/code/patches.html#check-list
-[3]: http://symfony.com/doc/current/contributing/code/patches.html#make-a-pull-request
+There is also a policy for contributing to this project. Pull requests must
+be explained step by step to make the review process easy in order to
+accept and merge them. New features must come paired with Unit and/or Functional
+tests.