Added note why getrs is used instead of getri
Added note why getrs is used instead of getri

wkentaro/chainer,hvy/chainer,okuta/chainer,okuta/chainer,chainer/chainer,chainer/chainer,hvy/chainer,niboshi/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,chainer/chainer,wkentaro/chainer,okuta/chainer,niboshi/chainer,pfnet/chainer,wkentaro/chainer,hvy/chainer,niboshi/chainer,niboshi/chainer,hvy/chainer