update doc

doc/doc_ch/detection.md

@@ -76,8 +76,8 @@ tar -xf ./pretrain_models/MobileNetV3_large_x0_5_pretrained.tar ./pretrain_model
 # 单机单卡训练 mv3_db 模型
 python3 tools/train.py -c configs/det/det_mv3_db.yml \
      -o Global.pretrain_weights=./pretrain_models/MobileNetV3_large_x0_5_pretrained/
-# 单机多卡训练，通过 --select_gpus 参数设置使用的GPU ID；
-python3 -m paddle.distributed.launch --selected_gpus '0,1,2,3' tools/train.py -c configs/det/det_mv3_db.yml \
+# 单机多卡训练，通过 --gpus 参数设置使用的GPU ID；如果使用的paddle版本小于2.0rc1，请使用'--select_gpus'参数选择要使用的GPU
+python3 -m paddle.distributed.launch --gpus '0,1,2,3' tools/train.py -c configs/det/det_mv3_db.yml \
      -o Global.pretrain_weights=./pretrain_models/MobileNetV3_large_x0_5_pretrained/
 ```
 

doc/doc_en/detection_en.md

@@ -76,8 +76,10 @@ You can also use `-o` to change the training parameters without modifying the ym
 python3 tools/train.py -c configs/det/det_mv3_db.yml -o Optimizer.base_lr=0.0001
 
 # multi-GPU training
-# Set the GPU ID used by the '--select_gpus' parameter;
-python3 -m paddle.distributed.launch --selected_gpus '0,1,2,3'  tools/train.py -c configs/det/det_mv3_db.yml -o Optimizer.base_lr=0.0001
+# Set the GPU ID used by the '--gpus' parameter; If your paddle version less than 2.0rc1, please use '--selected_gpus'
+python3 -m paddle.distributed.launch --gpus '0,1,2,3'  tools/train.py -c configs/det/det_mv3_db.yml -o Optimizer.base_lr=0.0001
+
+
 ```
 
 #### load trained model and continue training

train.sh

- python3 -m paddle.distributed.launch --selected_gpus '0,1,2,3,4,5,6,7'  tools/train.py -c configs/rec/rec_mv3_none_bilstm_ctc.yml
\ No newline at end of file
+# for paddle.__version__ >= 2.0rc1
+python3 -m paddle.distributed.launch --gpus '0,1,2,3,4,5,6,7'  tools/train.py -c configs/rec/rec_mv3_none_bilstm_ctc.yml
+
+# for paddle.__version__ < 2.0rc1
+# python3 -m paddle.distributed.launch --selected_gpus '0,1,2,3,4,5,6,7'  tools/train.py -c configs/rec/rec_mv3_none_bilstm_ctc.yml