Add some top level bevy crate docs

README.md

@@ -5,7 +5,7 @@
 
 ## What is Bevy?
 
-Bevy is a modern data-driven game engine built in Rust
+Bevy is a modular game engine built in Rust, with a focus on developer productivity and performance.
 
 ## WARNING
 

src/lib.rs

@@ -1,4 +1,19 @@
+//! Bevy is a modular game engine built in Rust, with a focus on developer productivity and performance.
+//! 
+//! It has the following design goals:
+//! * Provide a first class user-experience for both 2D and 3D games
+//! * Easy for newbies to pick up, but infinitely flexible for power users
+//! * Fast iterative compile times. Ideally less than 1 second for small to medium sized projects
+//! * Data-first game development using ECS (Entity Component Systems)
+//! * High performance and parallel architecture
+//! * Use the latest and greatest rendering technologies and techniques
+//! 
+//! The "bevy" crate is just a container crate that makes it easier to consume Bevy components.
+//! The defaults provide a "full" engine experience, but you can easily enable / disable features
+//! in your project's Cargo.toml to meet your specific needs. See Bevy's Cargo.toml for a full list of features available.
+
 #![feature(min_specialization)]
+
 pub mod prelude;
 
 pub use bevy_app as app;