made changes to run for more the one rnn cell

[zippermaan]

Made changes to make the code work on adding more than one RNN cell i.e num_layers > 1

[macanv]

谢谢，但是亲测不断叠加RNN会让模型效果降低，不知道你测试过没有。

[zippermaan]

I don't get what you exactly mean by superimposition, why did you even include it in the first place when you are doubtful of its performance.
Training with multiple RNN cell generally improves the performance, as I have observed with other models I have trained.