add note about tracking node 0.11 api
add note about tracking node 0.11 api

close #34

btd/buffer,LiuDeng/buffer,feross/buffer,LinusU/buffer,beni55/buffer,kawanet/buffer,btd/buffer,feross/buffer,LiuDeng/buffer,loon3/buffer,beni55/buffer,loon3/buffer,LinusU/buffer,SAGV/buffer,jessetane/buffer,SAGV/buffer,kawanet/buffer,feross/buffer,nolanlawson/buffer,nolanlawson/buffer