Update README: remove v2 from file references

Amp-Thread-ID: https://ampcode.com/threads/T-019c434e-990d-76bd-aab2-68b63d62e81f
Co-authored-by: Amp <amp@ampcode.com>

README.md

@@ -59,8 +59,8 @@ print(result)
 
 - `adapter_model.safetensors` — LoRA weights
 - `adapter_config.json` — LoRA config
-- `inference_v2.py` — inference script
-- `train_v2.py` — training script
+- `inference.py` — inference script
+- `train.py` — training script
 
 ## Known Issues