Update introduction_cn.ipynb (#5652)

modelcenter/PP-HelixFold/introduction_cn.ipynb

@@ -49,7 +49,7 @@
     "我们提供脚本`setup_env`来安装`conda`环境和所需的所有第三方工具库。您可以在`setup_env`中更改环境名字和CUDA版本。运行命令如下：\n",
     "```bash\n",
     "git clone https://github.com/PaddlePaddle/PaddleHelix.git # download PaddleHelix\n",
-    "cd https://github.com/PaddlePaddle/PaddleHelix/tree/dev/apps/protein_folding/helixfold\n",
+    "cd /apps/protein_folding/helixfold\n",
     "wget https://paddle-wheel.bj.bcebos.com/develop/linux/linux-gpu-cuda11.2-cudnn8-mkl-gcc8.2-avx/paddlepaddle_gpu-0.0.0.post112-cp37-cp37m-linux_x86_64.whl\n",
     "sh setup_env\n",
     "conda activate helixfold # activate the conda environment\n",