Updating the controller customization doc
Updating the controller customization doc

* Fix the last route declaration to its real use
* Use the term `make sure` instead of `check if` since it is should to work
* use the double `:` syntax for controllers instead of the deprecated single `:`
loic425/Sylius,antonioperic/Sylius,SyliusBot/Sylius,lchrusciel/Sylius,101medialab/Sylius,pamil/Sylius,101medialab/Sylius,Arminek/Sylius,Arminek/Sylius,Arminek/Sylius,GSadee/Sylius,pamil/Sylius,GSadee/Sylius,diimpp/Sylius,Sylius/Sylius,lchrusciel/Sylius,Zales0123/Sylius,antonioperic/Sylius,diimpp/Sylius,antonioperic/Sylius,Sylius/Sylius,Zales0123/Sylius,Zales0123/Sylius,SyliusBot/Sylius,diimpp/Sylius,loic425/Sylius,GSadee/Sylius,101medialab/Sylius,Sylius/Sylius,SyliusBot/Sylius,lchrusciel/Sylius,loic425/Sylius,pamil/Sylius