Update contributing guide
Update contributing guide

foobarflies/Sylius,Zales0123/Sylius,gmoigneu/platformsh-integrations,Mozan/Sylius,vihuvac/Sylius,mbabker/Sylius,itinance/Sylius,NeverResponse/Sylius,venyii/Sylius,dragosprotung/Sylius,gorkalaucirica/Sylius,pjedrzejewski/Sylius,pamil/Sylius,pjedrzejewski/Sylius,NeverResponse/Sylius,dragosprotung/Sylius,Arminek/Sylius,GSadee/Sylius,bitbager/Sylius,Joypricecorp/Sylius,venyii/Sylius,mbabker/Sylius,Sylius/Sylius,NeverResponse/Sylius,gseidel/Sylius,Mozan/Sylius,bitbager/Sylius,Zales0123/Sylius,gorkalaucirica/Sylius,antonioperic/Sylius,itinance/Sylius,SyliusBot/Sylius,Arminek/Sylius,ezecosystem/Sylius,loic425/Sylius,videni/Sylius,ylastapis/Sylius,mbabker/Sylius,Sylius/Sylius,diimpp/Sylius,101medialab/Sylius,Mozan/Sylius,Mozan/Sylius,pjedrzejewski/Sylius,pjedrzejewski/Sylius,lchrusciel/Sylius,Joypricecorp/Sylius,gmoigneu/platformsh-integrations,Arminek/Sylius,Brille24/Sylius,101medialab/Sylius,torinaki/Sylius,gmoigneu/platformsh-integrations,Joypricecorp/Sylius,Mozan/Sylius,lchrusciel/Sylius,ezecosystem/Sylius,dragosprotung/Sylius,dragosprotung/Sylius,videni/Sylius,diimpp/Sylius,gseidel/Sylius,itinance/Sylius,SyliusBot/Sylius,GSadee/Sylius,itinance/Sylius,kayue/Sylius,diimpp/Sylius,bitbager/Sylius,mbabker/Sylius,101medialab/Sylius,foobarflies/Sylius,ylastapis/Sylius,Brille24/Sylius,ezecosystem/Sylius,loic425/Sylius,pamil/Sylius,antonioperic/Sylius,venyii/Sylius,ylastapis/Sylius,gorkalaucirica/Sylius,ylastapis/Sylius,videni/Sylius,Brille24/Sylius,ezecosystem/Sylius,Zales0123/Sylius,gmoigneu/platformsh-integrations,kayue/Sylius,vihuvac/Sylius,torinaki/Sylius,gseidel/Sylius,foobarflies/Sylius,SyliusBot/Sylius,Brille24/Sylius,NeverResponse/Sylius,torinaki/Sylius,antonioperic/Sylius,torinaki/Sylius,videni/Sylius,pamil/Sylius,Sylius/Sylius,lchrusciel/Sylius,gorkalaucirica/Sylius,GSadee/Sylius,kayue/Sylius,loic425/Sylius,bitbager/Sylius,gseidel/Sylius,vihuvac/Sylius,foobarflies/Sylius,venyii/Sylius,vihuvac/Sylius,Joypricecorp/Sylius