[ci skip] Doc fix (loading trained model)

docs/modules/a2c.rst

@@ -62,7 +62,7 @@ Train a A2C agent on `CartPole-v1` using 4 processes.
 
   del model # remove to demonstrate saving and loading
 
-  A2C.load("a2c_cartpole")
+  model = A2C.load("a2c_cartpole")
 
   obs = env.reset()
   while True:

docs/modules/acer.rst

@@ -57,7 +57,7 @@ Example
 
   del model # remove to demonstrate saving and loading
 
-  ACER.load("acer_cartpole")
+  model = ACER.load("acer_cartpole")
 
   obs = env.reset()
   while True:

docs/modules/acktr.rst

@@ -58,7 +58,7 @@ Example
 
   del model # remove to demonstrate saving and loading
 
-  ACKTR.load("acktr_cartpole")
+  model = ACKTR.load("acktr_cartpole")
 
   obs = env.reset()
   while True:

docs/modules/ddpg.rst

@@ -66,7 +66,7 @@ Example
 
   del model # remove to demonstrate saving and loading
 
-  DDPG.load("ddpg_mountain")
+  model = DDPG.load("ddpg_mountain")
 
   obs = env.reset()
   while True:

docs/modules/dqn.rst

@@ -58,7 +58,7 @@ Example
 
   del model # remove to demonstrate saving and loading
 
-  DQN.load("deepq_cartpole")
+  model = DQN.load("deepq_cartpole")
 
   obs = env.reset()
   while True:

docs/modules/ppo2.rst

@@ -73,7 +73,7 @@ Train a PPO agent on `CartPole-v1` using 4 processes.
 
    del model # remove to demonstrate saving and loading
 
-   PPO2.load("ppo2_cartpole")
+   model = PPO2.load("ppo2_cartpole")
 
    # Enjoy trained agent
    obs = env.reset()

docs/modules/trpo.rst

@@ -57,7 +57,7 @@ Example
 
   del model # remove to demonstrate saving and loading
 
-  TRPO.load("trpo_cartpole")
+  model = TRPO.load("trpo_cartpole")
 
   obs = env.reset()
   while True: