Update functions.rst
Update functions.rst

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