[doc fix] fix detr docs, test=document_fix (#3873)

configs/deformable_detr/README.md

@@ -17,6 +17,12 @@ Deformable DETR is an object detection model based on DETR. We reproduced the mo
 - Deformable DETR is trained on COCO train2017 dataset and evaluated on val2017 results of `mAP(IoU=0.5:0.95)`.
 - Deformable DETR uses 8GPU to train 50 epochs.
 
+GPU multi-card training
+```bash
+export CUDA_VISIBLE_DEVICES=0,1,2,3,4,5,6,7
+python -m paddle.distributed.launch --gpus 0,1,2,3,4,5,6,7 tools/train.py -c configs/deformable_detr/deformable_detr_r50_1x_coco.yml --fleet -o find_unused_parameters=True
+```
+
 ## Citations
 ```
 @inproceedings{

configs/detr/README.md

@@ -17,6 +17,12 @@ DETR is an object detection model based on transformer. We reproduced the model
 - DETR is trained on COCO train2017 dataset and evaluated on val2017 results of `mAP(IoU=0.5:0.95)`.
 - DETR uses 8GPU to train 500 epochs.
 
+GPU multi-card training
+```bash
+export CUDA_VISIBLE_DEVICES=0,1,2,3,4,5,6,7
+python -m paddle.distributed.launch --gpus 0,1,2,3,4,5,6,7 tools/train.py -c configs/detr/detr_r50_1x_coco.yml --fleet -o find_unused_parameters=True
+```
+
 ## Citations
 ```
 @inproceedings{detr,