`cargo component build` does not add `mod bindings` to `main.rs`

When I walked through the tutorial in https://component-model.bytecodealliance.org/language-support/rust.html#importing-an-interface-into-a-command-component with my own adder example, after Step 3 adding `package.metadata.component.target.dependencies` and running `cargo build component`, I found `bindings.rs` was generated under `src` folder, but `mod bindings` was not added to `main.rs`.

`main.rs` was initially created by `cargo component new my-command-component` with the content
```rust
fn main() {
println!("Hello World");
}
```

I think after generating `bindings.rs`, `cargo-component` should automatically attach it to `main.rs`.