Update setup.rst

[deverman]

To run the symfony app it should be under symfony 3

php app/console server:run

[xabbuh]

Since Symfony 3.0 the console in the Symfony Standard Edition is located in the bin/ directory. Which steps did you follow to end up having it under app/?

[javiereguiluz]

Closing it as "won't fix" because in Symfony 3.x you must use bin/console by default ... The app/console script is for any version prior to 3.x (2.3, 2.7, 2.8, etc.) In nay case, thanks for helping us review and double check the docs!