Provide contribution guidelines

CONTRIBUTING.md

@@ -0,0 +1,38 @@
+Contributing
+============
+
+First of all, **thank you** for contributing, **you are awesome**!
+
+Here are a few rules to follow in order to ease code reviews, and discussions before
+maintainers accept and merge your work.
+
+You MUST follow the [PSR-1](http://www.php-fig.org/psr/1/) and
+[PSR-2](http://www.php-fig.org/psr/2/). If you don't know about any of them, you
+should really read the recommendations. Can't wait? Use the [PHP-CS-Fixer
+tool](http://cs.sensiolabs.org/).
+
+You MUST run the test suite.
+
+You MUST write (or update) unit tests.
+
+You SHOULD write documentation.
+
+Please, write [commit messages that make
+sense](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html),
+and [rebase your branch](http://git-scm.com/book/en/Git-Branching-Rebasing)
+before submitting your Pull Request.
+
+One may ask you to [squash your
+commits](http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html)
+too. This is used to "clean" your Pull Request before merging it (we don't want
+commits such as `fix tests`, `fix 2`, `fix 3`, etc.).
+
+Thank you!
+
+## Running the test suite
+
+Ensure that the required vendors are installed by running `composer install`.
+The test suite requires the `php5-mongo` extension to be installed.
+
+PHPUnit should be installed by composer. Run the tests with the
+`./vendor/bin/phpunit` command.

README.md

@@ -25,6 +25,10 @@ If upgrading from a previous version, also check:
 
 [UPGRADE.md](https://github.com/dustin10/VichUploaderBundle/blob/master/UPGRADE.md)
 
-For license, see:
+## Contributing
 
-[Resources/meta/LICENSE](https://github.com/dustin10/VichUploaderBundle/blob/master/Resources/meta/LICENSE)
+See the [CONTRIBUTING](https://github.com/dustin10/VichUploaderBundle/blob/master/CONTRIBUTING.md) file.
+
+## License
+
+See the bundled [LICENSE](https://github.com/dustin10/VichUploaderBundle/blob/master/Resources/meta/LICENSE) file.