This is only a Boids project, now. Drop others.

The examples and learning plugins have outlived their usefulness, and
this repo already has substantial history in being a boids plugin. I'm
renaming the crate (and repo, but that isn't visible to git) to treat
this simply as a boids repo.

src/main.rs

@@ -1,8 +1,6 @@
 use bevy::prelude::*;
 
 mod birdoids_plugin;
-mod breakout_plugin;
-mod hello_world_plugin;
 
 use birdoids_plugin::BoidsPlugin;