Removed dev stability flag from readme [skip ci]

Author: samdark

README.md

@@ -51,7 +51,7 @@ at [getcomposer.org](http://getcomposer.org/doc/00-intro.md#installation-nix).
 You can then install this project template using the following command:
 
 ~~~
-php composer.phar create-project --prefer-dist --stability=dev yiisoft/yii2-app-basic basic
+composer create-project --prefer-dist yiisoft/yii2-app-basic basic
 ~~~
 
 Now you should be able to access the application through the following URL, assuming `basic` is the directory