change the ribbon example into a tracer example.

[naasblod]

I think this could be more helpful for people wanting to use the ribbon example. In my mind "tracers" are the most used application for this sort of thing, If you feel it isn't just close it.

run with:
cargo run --example ribbon --features="bevy/bevy_winit bevy/bevy_pbr 3d bevy/bevy_gizmos"

[djeedai]

If I understand correctly you're proposing to replace the purely GPU driven motion with a property-based one, to show how a ribbon can follow a target as a kind of trail, is that it?

I don't have any objection, but if you feel that tracers are common (I don't have an opinion, probably that's correct) then I'd expand a tiny bit the top level documentation to mention that this example shows a "tracer" (so that if someone search that term they find that example) and explain how a property is used to link the particle position to some CPU position (as this is probably a common feature to want).

[naasblod]

Screen.Recording.2024-10-15.at.21.23.02.mov