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

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