add: documents feature flags (#147)

* add: documents feature flags
esspecially the multicam feature

* doc: documents requirement for `CosmicPrimaryCamera`

* add: `CosmicPrimaryCamera` implements Debug and Default
for convenience

* fix: lints fixed

Cargo.toml

@@ -11,6 +11,8 @@ keywords = ["bevy"]
 exclude = ["assets/*"]
 
 [features]
+## Enable to avoid panicing when multiple cameras are used in the same world
+## Requires you to add `CosmicPrimaryCamera` marker component to the primary camera
 multicam = []
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
@@ -36,6 +38,8 @@ unicode-segmentation = { version = "1.11.0" }
 crossbeam-channel = "0.5.8"
 image = "0.24.6"
 sys-locale = "0.3.0"
+document-features = "0.2.8"
+
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 arboard = "3.2.0"
 

src/lib.rs

@@ -74,6 +74,9 @@
 //! | 0.12.* | 0.15             |
 //! | 0.11.* | 0.8 - 0.14       |
 //!
+//! ## Feature flags
+#![doc = document_features::document_features!()]
+//!
 //! ## License
 //!
 //! MIT or Apache-2.0
@@ -148,8 +151,37 @@ impl Plugin for CosmicEditPlugin {
     }
 }
 
+/// Attach to primary camera, and enable the `multicam` feature to use multiple cameras.
+/// Will panic if no `Camera`s without this component exist and the `multicam` feature is enabled.
+///
+/// A very basic example which doesn't panic:
+/// ```rust
+/// use bevy::prelude::*;
+/// use bevy_cosmic_edit::CosmicPrimaryCamera;
+///
+/// fn main() {
+///   App::new()
+///     .add_plugins((
+///       DefaultPlugins,
+///       bevy_cosmic_edit::CosmicEditPlugin::default(),
+///     ))
+///     .add_systems(Startup, setup)
+///     .run();
+/// }
+///
+/// fn setup(mut commands: Commands) {
+///   commands.spawn((Camera3dBundle::default(), CosmicPrimaryCamera));
+///   commands.spawn(Camera3dBundle {
+///     camera: Camera {
+///       order: 2,
+///       ..default()
+///     },
+///     ..default()
+///   });
+/// }
+/// ```
 #[cfg(feature = "multicam")]
-#[derive(Component)]
+#[derive(Component, Debug, Default)]
 pub struct CosmicPrimaryCamera;
 
 /// Resource struct that holds configuration options for cosmic fonts.

src/user_select.rs

@@ -10,7 +10,7 @@ impl Plugin for UserSelectPlugin {
 }
 
 /// Tag component to disable user selection
-/// Like CSS `user-select: none` https://developer.mozilla.org/en-US/docs/Web/CSS/user-select
+/// Like CSS `user-select: none` <https://developer.mozilla.org/en-US/docs/Web/CSS/user-select>
 #[derive(Component, Default)]
 pub struct UserSelectNone;