[tools/onnx-subgraph] add guide in README.md for subgraphs verification

tools/onnx_subgraph/README.md

@@ -61,17 +61,15 @@ sub models.
     └── NPUsubgraph1.onnx
 ```
 ## Verify the subgraphs inference with original model file
-    compare the MSE of original inference result and subgraphs inference result
+compare the MSE of original inference result and subgraphs inference result
 ```bash
     python scripts/single_vs_multiple_onnx.py \
            -s ./resnet-test.onnx \
            -m ./subgraphs/ \
            -n scripts/subgraphs_ios.txt
 ```
-    output:
-```bash
-    Single model inference completed!
-    Multiple subgraph inference completed!
-    Comparing inference results between single ONNX model and multiple subgraphs...
-    Output '316' MSE: 5.125894080395578e-14
-```
+output:
+Single model inference completed!
+Multiple subgraph inference completed!
+Comparing inference results between single ONNX model and multiple subgraphs...
+Output '316' MSE: 5.125894080395578e-14