fix some doc tests

crates/bevy_ecs/hecs/src/lib.rs

@@ -33,7 +33,7 @@
 //! let a = world.spawn((123, true, "abc"));
 //! let b = world.spawn((42, false));
 //! // Systems can be simple for loops
-//! for (id, number, &flag) in &mut world.query::<(Entity, &mut i32, &bool)>() {
+//! for (id, mut number, &flag) in &mut world.query::<(Entity, &mut i32, &bool)>() {
 //!   if flag { *number *= 2; }
 //! }
 //! assert_eq!(*world.get::<i32>(a).unwrap(), 246);

crates/bevy_ecs/hecs/src/world.rs

@@ -272,7 +272,7 @@ impl World {
     /// let a = world.spawn((123, true, "abc"));
     /// // The returned query must outlive the borrow made by `get`
     /// let mut query = world.query_one::<(&mut i32, &bool)>(a).unwrap();
-    /// let (number, flag) = query.get().unwrap();
+    /// let (mut number, flag) = query.get().unwrap();
     /// if *flag { *number *= 2; }
     /// assert_eq!(*number, 246);
     /// ```

src/lib.rs

@@ -8,12 +8,11 @@
 //!
 //! ## Example
 //!Here is a simple "Hello World" Bevy app:
-//! ```no_run
+//! ```
 //!use bevy::prelude::*;
 //!
 //!fn main() {
 //!    App::build()
-//!        .add_default_plugins()
 //!        .add_system(hello_world_system.system())
 //!        .run();
 //!}