update README.md.

Signed-off-by: 葛峻恺 <202115006@mail.sdu.edu.cn>

README.md

@@ -77,7 +77,7 @@ GPR-SIDL-inv/
 
     ├── 9_time_depth_convert.py        # Convert the predicted results into the deep domain through integration
 
-    ├── config.yaml                    # Configuration file, used to define all paths, variables, and parameters
+    ├── config.py                    # Configuration file, used to define all paths, variables, and parameters
 
     ├── requirements.txt               # Python dependencies