Add UPGRADE note for payum version
Add UPGRADE note for payum version

Zales0123/Sylius,SyliusBot/Sylius,loic425/Sylius,SyliusBot/Sylius,101medialab/Sylius,Zales0123/Sylius,diimpp/Sylius,diimpp/Sylius,diimpp/Sylius,loic425/Sylius,Sylius/Sylius,Sylius/Sylius,SyliusBot/Sylius,lchrusciel/Sylius,Zales0123/Sylius,lchrusciel/Sylius,101medialab/Sylius,lchrusciel/Sylius,Sylius/Sylius,101medialab/Sylius,loic425/Sylius