Update "CONTRIBUTING.md" file

CONTRIBUTING.md

@@ -8,7 +8,7 @@ pull requests for new features must be based on `master`.
 
 Due to time constraints, we are not always able to respond as quickly as we
 would like. Please do not take delays personal and feel free to remind us here,
-on IRC or on Gitter if you feel that we forgot to respond.
+on IRC, or on Gitter if you feel that we forgot to respond.
 
 ## Using Respect\Config From a Git Checkout
 
@@ -22,7 +22,7 @@ cd Config
 Retrieve Respect\Config's dependencies using [Composer](http://getcomposer.org/):
 
 ```shell
-composer install --dev
+composer install
 ```
 
 ## Running Tests
@@ -45,6 +45,14 @@ You can test the project using the commands:
 
 No test should fail.
 
+You can tweak the PHPUnit's settings by copying `phpunit.xml.dist` to `phpunit.xml`
+and changing it according to your needs.
+
+## Standards
+
+We are trying to follow the [PHP-FIG](http://www.php-fig.org)'s standards, so
+when you send us a pull request, be sure you are following them.
+
 ## Sending your code to us
 
 Please see http://help.github.com/pull-requests/.