Idiomatic way of adding a startup system in 0.10?

[keithsharp]

I've seen both of these patterns used in the documentation and examples:

App::new()
    .add_startup_system(add_people_system)
    .add_system(greet_people_system)
    .run()

or

App::new()
    .add_systems((
        add_people_system.on_startup(),
        greet_people_system,
    ))
    .run();

and was wondering which I should be preferring, and why?

[NiklasEi]

This is very much connected to the discussion in #8005
You can find some pro/contra arguments in there.

It's not yet clear what the API should look like to add systems to schedules (startup systems get collected in a startup schedule). I personally prefere your second example, but you can currently use both approaches.