Fix docs in n_step_rnn.py
Fix docs in n_step_rnn.py

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