[Enhance] Update README document in Project (open-mmlab#9599)

Author: BIGWangYuDong

projects/SparseInst/README.md

@@ -48,7 +48,7 @@ python -m torch.distributed.launch --nnodes=1 --node_rank=0 --nproc_per_node=${N
 In MMDetection's root directory, run the following command to test the model:
 
 ```bash
-python tools/train.py projects/SparseInst/configs/sparseinst_r50_iam_8xb8-ms-270k_coco.py ${CHECKPOINT_PATH}
+python tools/test.py projects/SparseInst/configs/sparseinst_r50_iam_8xb8-ms-270k_coco.py ${CHECKPOINT_PATH}
 ```
 
 ## Results

projects/example_project/README.md

@@ -22,6 +22,12 @@ In MMDetection's root directory, run the following command to train the model:
 python tools/train.py projects/example_project/configs/faster-rcnn_dummy-resnet_fpn_1x_coco.py
 ```
 
+For multi-gpu training, run:
+
+```bash
+python -m torch.distributed.launch --nnodes=1 --node_rank=0 --nproc_per_node=${NUM_GPUS} --master_port=29506 --master_addr="127.0.0.1" tools/train.py projects/example_project/configs/faster-rcnn_dummy-resnet_fpn_1x_coco.py
+```
+
 ### Testing commands
 
 In MMDetection's root directory, run the following command to test the model: