Update gradio.Interface examples

app.py

@@ -25,6 +25,7 @@ iface = gr.Interface(
         "cat /proc/version  # show linux distro",
         "free  # show free memory",
         "uname -m  # show machine arch ",
+        "df -h . # show disk space ",
         "cat /proc/cpuinfo  # show cpu info ",
     ],
     title="probe the system",