add roi_max_align_2d doc
add roi_max_align_2d doc

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