Fix brain name (#1349)

config/offline_bc_config.yaml

     memory_size: 256
     demo_path: ./UnitySDK/Assets/Demonstrations/<Your_Demon_File>.demo
 
-HallwayBrain:
+HallwayLearning:
     trainer: offline_bc
     max_steps: 5.0e5
     num_epoch: 5
     use_recurrent: true
     memory_size: 256
     sequence_length: 32
-    demo_path: ./UnitySDK/Assets/Demonstrations/Hallway.demo
+    demo_path: ./UnitySDK/Assets/Demonstrations/Hallway.demo