Contribute-to-Git:-A-beginner's-Guide.md

@@ -80,7 +80,7 @@ Sometimes, you would want to extract from the mailing list and apply them to you
 1. Install b4
 
 <details><summary>MacOS</summary>
-```
+    ```shell
     python3 -m venv <path/to/venv>
     source <path/to/venv>/bin/activate
     python3 -m pip install b4