address comment
address comment

* fix doc.

hvy/chainer,wkentaro/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,wkentaro/chainer,hvy/chainer,okuta/chainer,niboshi/chainer,pfnet/chainer,keisuke-umezawa/chainer,wkentaro/chainer,niboshi/chainer,okuta/chainer,niboshi/chainer,okuta/chainer,hvy/chainer,okuta/chainer,chainer/chainer,keisuke-umezawa/chainer,hvy/chainer,tkerola/chainer,chainer/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer,chainer/chainer