Docs around observer Trigger::components() is not clear

[cBournhonesque]

How can Bevy's documentation be improved?

The docs here mention that the trigger components will be

the components that triggered the observer, out of the
    /// components defined in `B`

That is not the observed behaviour

world.spawn(
    Observer::new(|trigger: Trigger<OnAdd, A>| {
        dbg!(trigger.components());
    })
);
let mut entity = world.spawn((A, B));

When the observer runs, the trigger.components() will contain the component ids for A and B.