stm32: add usb_hid_mouse example

Signed-off-by: Vo Trung Chi <chi.votrung@vn.bosch.com>

examples/stm32f4/src/bin/usb_hid_mouse.rs

@@ -119,9 +119,9 @@ async fn main(_spawner: Spawner) {
         }
     };
 
-// Run everything concurrently.
+    // Run everything concurrently.
-// If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
-join(usb_fut, hid_fut).await;
+    join(usb_fut, hid_fut).await;
 }
 
 struct MyRequestHandler {}