!2940 fix gat train fail caused by checkpoint permission and missing data path in README.MD

Merge pull request !2940 from zhangdengcheng/master

model_zoo/gat/README.md

@@ -72,9 +72,9 @@ sh run_process_data.sh [SRC_PATH] [DATASET_NAME]
 >> Launch
 ```
 #Generate dataset in mindrecord format for cora
-sh run_process_data.sh cora
+./run_process_data.sh ./data cora
 #Generate dataset in mindrecord format for citeseer
-sh run_process_data.sh citeseer
+./run_process_data.sh ./data citeseer
 ```
 
 # Features

model_zoo/gat/train.py

@@ -96,6 +96,8 @@ def train():
             if eval_acc >= val_acc_max and eval_loss < val_loss_min:
                 val_acc_model = eval_acc
                 val_loss_model = eval_loss
+                if os.path.exists("ckpts/gat.ckpt"):
+                    os.remove("ckpts/gat.ckpt")
                 _exec_save_checkpoint(train_net.network, "ckpts/gat.ckpt")
             val_acc_max = np.max((val_acc_max, eval_acc))
             val_loss_min = np.min((val_loss_min, eval_loss))