Missing migration: mention features to enable for reflection registration to work #21092
Description
What problem does this solve or what need does it fill?
Porting Tnua, I got this:
thread 'main' (253822) panicked at /home/hhh/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/bevy_scene-0.17.0-rc.1/src/scene_spawner.rs:621:35:
scene contains the unregistered type `bevy_transform::components::transform::Transform`. consider reflecting it with `#[derive(Reflect)]` and registering the type using `app.register_type::<T>()`
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Encountered a panic in system `bevy_scene::scene_spawner::scene_spawner_system`!
Encountered a panic in system `bevy_app::main_schedule::Main::run_main`!
error: command `cargo run --bin platformer_3d --features avian3d,bevy/debug --profile dev` exited with status code exit status: 101
This happened because bevy_tnua depends on Bevy without default features enabled. Turns out you need to enable reflect_auto_register for that to work. Also, the new reflect_auto_register_static feature is not mentioned either.