Update CONTRIBUTING.md

Author: programeriss

CONTRIBUTING.md

@@ -1,30 +1,23 @@
 # Contributing
 
-Contributions are **welcome** and will be fully **credited**.
+Contributions are **welcome**.
 
 We accept contributions via Pull Requests on [Github](https://github.com/thephpleague/pdf-to-image).
 
 
 ## Pull Requests
 
-- **[PSR-2 Coding Standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md)** - The easiest way to apply the conventions is to install [PHP Code Sniffer](http://pear.php.net/package/PHP_CodeSniffer).
-
-- **Add tests!** - Your patch won't be accepted if it doesn't have tests.
-
 - **Document any change in behaviour** - Make sure the `README.md` and any other relevant documentation are kept up-to-date.
 
 - **Create feature branches** - Don't ask us to pull from your master branch.
 
 - **One pull request per feature** - If you want to do more than one thing, send multiple pull requests.
 
-- **Send coherent history** - Make sure each individual commit in your pull request is meaningful. If you had to make multiple intermediate commits while developing, please [squash them](http://www.git-scm.com/book/en/v2/Git-Tools-Rewriting-History#Changing-Multiple-Commit-Messages) before submitting.
-
-
 ## Running Tests
 
 ``` bash
 $ phpunit
 ```
 
 
-**Happy coding**!
+**Happy coding**!