README: Move sections around a bit
README: Move sections around a bit

It makes sense to keep the "Usage" section close to the "Quick start" section, so let's do that!
chelmertz/spotifile,catharsis/spotifile,raoulh/spotifile,chelmertz/spotifile,catharsis/spotifile,catharsis/spotifile,raoulh/spotifile,raoulh/spotifile,chelmertz/spotifile