add example of renamed optimizer hook
add example of renamed optimizer hook

okuta/chainer,rezoo/chainer,niboshi/chainer,niboshi/chainer,chainer/chainer,pfnet/chainer,ktnyt/chainer,ronekko/chainer,ktnyt/chainer,anaruse/chainer,okuta/chainer,keisuke-umezawa/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,tkerola/chainer,ktnyt/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,hvy/chainer,wkentaro/chainer,jnishi/chainer,niboshi/chainer,hvy/chainer,jnishi/chainer,ktnyt/chainer,okuta/chainer,chainer/chainer,jnishi/chainer,wkentaro/chainer,hvy/chainer,wkentaro/chainer,chainer/chainer,keisuke-umezawa/chainer,niboshi/chainer,jnishi/chainer,hvy/chainer