fixes simple grammatical mistake in tutorial
fixes simple grammatical mistake in tutorial

wkentaro/chainer,chainer/chainer,okuta/chainer,AlpacaDB/chainer,ktnyt/chainer,rezoo/chainer,aonotas/chainer,kikusu/chainer,kashif/chainer,wkentaro/chainer,tscohen/chainer,cupy/cupy,jnishi/chainer,AlpacaDB/chainer,ysekky/chainer,wkentaro/chainer,cupy/cupy,muupan/chainer,truongdq/chainer,cupy/cupy,benob/chainer,niboshi/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,okuta/chainer,niboshi/chainer,hvy/chainer,jnishi/chainer,wkentaro/chainer,t-abe/chainer,ktnyt/chainer,jnishi/chainer,sinhrks/chainer,benob/chainer,hvy/chainer,hvy/chainer,hvy/chainer,muupan/chainer,truongdq/chainer,niboshi/chainer,tkerola/chainer,okuta/chainer,cemoody/chainer,keisuke-umezawa/chainer,pfnet/chainer,ronekko/chainer,jnishi/chainer,kikusu/chainer,t-abe/chainer,niboshi/chainer,minhpqn/chainer,chainer/chainer,keisuke-umezawa/chainer,cupy/cupy,ktnyt/chainer,delta2323/chainer,chainer/chainer,okuta/chainer,ktnyt/chainer,sinhrks/chainer,chainer/chainer,kiyukuta/chainer,anaruse/chainer