Use single quotes and project_dir parameter

Author: yceruto

app/config/config.yml

@@ -13,7 +13,7 @@ framework:
     #translator: { fallbacks: ['%locale%'] }
     secret: '%secret%'
     router:
-        resource: '%kernel.root_dir%/config/routing.yml'
+        resource: '%kernel.project_dir%/app/config/routing.yml'
         strict_requirements: ~
     form: ~
     csrf_protection: ~