docs(readme): use promise instead of yield
docs(readme): use promise instead of yield

nodkz/graffiti-mongoose,relax/graffiti-mongoose,tothandras/graffiti-mongoose,parkan/graffiti-mongoose,hardchor/graffiti-mongoose,RisingStack/graffiti-mongoose,relax/graffiti-mongoose,relax/graffiti-mongoose,brysgo/graffiti-mongoose