Fix docstring.
Fix docstring.

cupy/cupy,anaruse/chainer,chainer/chainer,hvy/chainer,keisuke-umezawa/chainer,ktnyt/chainer,kashif/chainer,okuta/chainer,niboshi/chainer,niboshi/chainer,cupy/cupy,jnishi/chainer,ktnyt/chainer,pfnet/chainer,chainer/chainer,niboshi/chainer,ktnyt/chainer,cupy/cupy,niboshi/chainer,keisuke-umezawa/chainer,okuta/chainer,ronekko/chainer,wkentaro/chainer,ysekky/chainer,keisuke-umezawa/chainer,jnishi/chainer,hvy/chainer,jnishi/chainer,wkentaro/chainer,hvy/chainer,okuta/chainer,rezoo/chainer,chainer/chainer,wkentaro/chainer,chainer/chainer,aonotas/chainer,wkentaro/chainer,jnishi/chainer,okuta/chainer,kiyukuta/chainer,hvy/chainer,tkerola/chainer,keisuke-umezawa/chainer,cupy/cupy,ktnyt/chainer,delta2323/chainer