Update rust_example.rs

Author: alex

drivers/char/rust_example.rs

@@ -137,7 +137,8 @@ impl KernelModule for RustExample {
         let mut chrdev_reg =
             chrdev::Registration::new_pinned(cstr!("rust_chrdev"), 0, &THIS_MODULE)?;
         // Register the same kind of device twice, we're just demonstrating
-        // that you can use multiple minors.
+        // that you can use multiple minors. There are two minors in this case
+        // because its type is `chrdev::Registration<2>`
         chrdev_reg.as_mut().register::<RustFile>()?;
         chrdev_reg.as_mut().register::<RustFile>()?;