Update README.MD svtplay-dl apt repo added for ubuntu/debian
Update README.MD svtplay-dl apt repo added for ubuntu/debian

Added instruction on how to use the svtplay-dl apt repo to install on debian and ubuntu, to avoid getting old version from official repo.
olof/svtplay-dl,selepo/svtplay-dl,olof/svtplay-dl,dalgr/svtplay-dl,spaam/svtplay-dl,dalgr/svtplay-dl,selepo/svtplay-dl,spaam/svtplay-dl