use cartpole-v0 in dqn (#259)

* use cartpole-v0 in dqn

* Update README.md

examples/DQN/README.md

@@ -6,7 +6,7 @@ Based on PARL, we provide a simple demonstration of DQN.
 
 ### Result
 
-Performance of DQN playing CartPole-v1
+Performance of DQN playing CartPole-v0
 
 <p align="left">
 <img src="../QuickStart/performance.gif" alt="result" height="175"/>
@@ -23,7 +23,7 @@ Performance of DQN playing CartPole-v1
 
 ### Start Training:
 ```
-# To train a model for CartPole-v1 game
+# To train a model for CartPole-v0 game
 python train.py
 ```
 

examples/DQN/train.py

@@ -73,7 +73,7 @@ def evaluate(agent, env, render=False):
 
 
 def main():
-    env = gym.make('CartPole-v1')
+    env = gym.make('CartPole-v0')
     action_dim = env.action_space.n
     obs_shape = env.observation_space.shape