Update README.md

Author: iYiYaHa

README.md

@@ -12,6 +12,7 @@ Please refer to requirements.txt
 
 ## Project Structure 
 
+```
 .
 ├── config.py (Configurations about IRGAN and BPR.)
 ├── data (Data Files)
@@ -41,9 +42,10 @@ Please refer to requirements.txt
 │   ├── pretrained_model_dns.pkl
 │   └── pretrained_model_sns.pkl
 ├── readme.md
+```
 
 ## How to run
 1. Execute **conda create --name <env_name> --file requirements.txt** to create an virtual environment and install required packages.
 2. Run a jupyter notebook server by **jupyter notebook**.
 3. Open IRGAN-SGD-dns-gen.ipynb in a browser and run all cells. 
-   The output of loss and other evaluation metrics can be observed with tensorboard.(Other notebooks from the *exp_notebooks* directory can be moved out to its upper-level directory and run). 
+   The output of loss and other evaluation metrics can be observed with tensorboard.(Other notebooks from the *exp_notebooks* directory can be moved out to its upper-level directory and run).