Add known errors section to UPGRADE file
Add known errors section to UPGRADE file

lchrusciel/Sylius,antonioperic/Sylius,itinance/Sylius,mbabker/Sylius,foobarflies/Sylius,pjedrzejewski/Sylius,pamil/Sylius,Zales0123/Sylius,pamil/Sylius,Zales0123/Sylius,SyliusBot/Sylius,pjedrzejewski/Sylius,foobarflies/Sylius,101medialab/Sylius,Sylius/Sylius,GSadee/Sylius,antonioperic/Sylius,diimpp/Sylius,Brille24/Sylius,GSadee/Sylius,pamil/Sylius,kayue/Sylius,kayue/Sylius,Arminek/Sylius,diimpp/Sylius,loic425/Sylius,loic425/Sylius,mbabker/Sylius,foobarflies/Sylius,mbabker/Sylius,lchrusciel/Sylius,GSadee/Sylius,Arminek/Sylius,kayue/Sylius,Brille24/Sylius,lchrusciel/Sylius,foobarflies/Sylius,Brille24/Sylius,Brille24/Sylius,itinance/Sylius,mbabker/Sylius,Sylius/Sylius,SyliusBot/Sylius,Arminek/Sylius,antonioperic/Sylius,pjedrzejewski/Sylius,Sylius/Sylius,101medialab/Sylius,diimpp/Sylius,itinance/Sylius,pjedrzejewski/Sylius,101medialab/Sylius,loic425/Sylius,SyliusBot/Sylius,itinance/Sylius,Zales0123/Sylius