[Merged by Bors] - Enable mdlint in CI

.github/bors.toml

@@ -1,5 +1,6 @@
 status = [
     "build",
+    "markdownlint",
 ]
 
 use_squash_merge = true

.github/linters/.markdown-lint.yml

@@ -0,0 +1,7 @@
+# Keep synced with duplicate in project root
+
+{
+    "line-length": false,
+    "no-inline-html": false,
+    "no-trailing-punctuation": false,
+}

.github/workflows/ci.yml

@@ -35,6 +35,22 @@ jobs:
           BUILD_ONLY: true
           TOKEN: fake-secret
 
+  markdownlint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          # Full git history is needed to get a proper list of changed files within `super-linter`
+          fetch-depth: 0
+      - name: Run Markdown Lint
+        uses: docker://ghcr.io/github/super-linter:slim-v4
+        env:
+          VALIDATE_ALL_CODEBASE: false
+          VALIDATE_MARKDOWN: true
+          DEFAULT_BRANCH: master
+          # Not needed here as only one Linter is used.
+          #GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
   test-code:
      runs-on: ubuntu-latest
      steps:

.markdownlint.yml

@@ -0,0 +1,7 @@
+# Keep synced with duplicate in .github/linters folder
+
+{
+    "line-length": false,
+    "no-inline-html": false,
+    "no-trailing-punctuation": false,
+}

content/learn/book/assets/hot-reloading/_index.md

@@ -9,4 +9,4 @@ insert_anchor_links = "right"
 
 TODO: demonstrate how to watch for changes to automatically hot reload assets when modified
 
-Steal from https://github.com/bevyengine/bevy/blob/main/examples/asset/hot_asset_reloading.rs
+Steal from [hot reloading example](https://github.com/bevyengine/bevy/blob/main/examples/asset/hot_asset_reloading.rs)

content/learn/book/development-practices/fast-compiles/_index.md

@@ -29,15 +29,15 @@ TODO: explain why you might want faster compiles
   * **Arch**: `sudo pacman -S lld`
   * **Windows**: Ensure you have the latest [cargo-binutils](https://github.com/rust-embedded/cargo-binutils)
 
-	```sh
-	cargo install -f cargo-binutils
-	rustup component add llvm-tools-preview
-	```
+ ```sh
+ cargo install -f cargo-binutils
+ rustup component add llvm-tools-preview
+ ```
 
-  * **MacOS**: Modern LLD does not yet support MacOS, but we can use zld instead: `brew install michaeleisel/zld/zld`
+* **MacOS**: Modern LLD does not yet support MacOS, but we can use zld instead: `brew install michaeleisel/zld/zld`
 * **Nightly Rust Compiler**: This gives access to the latest performance improvements and "unstable" optimizations
 
-	```sh
+ ```sh
     # Install the nightly toolchain
     rustup toolchain install nightly
     # Configure your current project to use nightly (run this command within the project)

content/learn/book/game-logic/system-ordering/_index.md

@@ -16,4 +16,4 @@ TODO: explain SystemSets in the context of labels
 
 TODO: explain ambiguities
 
-Steal from https://github.com/bevyengine/bevy/blob/main/examples/ecs/ecs_guide.rs#L282
+Steal from [ECS Guide](https://github.com/bevyengine/bevy/blob/main/examples/ecs/ecs_guide.rs#L282)

content/learn/book/migration-guides/0.4-0.5/_index.md

@@ -62,6 +62,7 @@ commands.entity(entity).despawn();
 `commands.spawn()` no longer accepts any parameters.  To spawn bundles, use `commands.spawn_bundle(bundle)`.
 
 Similarly, rather than using `with(some_component)` to spawn an object with multiple components, you must now use `insert(some_component)`:
+
 ```rust
 // 0.4
 commands.spawn(some_bundle)
@@ -78,6 +79,7 @@ commands.spawn()
 ```
 
 Removing and adding components on entities has also been changed:
+
 ```rust
 // 0.4
 commands.insert_one(some_entity, SomeComponent);
@@ -130,9 +132,11 @@ fn event_reader_system(mut my_event_reader: EventReader<MyEvent>) {
     }
 }
 ```
+
 You no longer need two system parameters to read your events. One `EventReader` is sufficient.
 
 Following the above example of using an `EventReader` to read events, you can now use `EventWriter` to create new ones.
+
 ```rust
 // 0.4
 fn event_writer_system(
@@ -188,7 +192,9 @@ TextBundle {
 ```
 
 ### Scene must now be specified when loading a GLTF scene
+
 Previously, you were able to load a GLTF scene asset with only a path. Now, you must include a fragment specifying the scene you want to load. If you only have one scene in the file, it's `#Scene0`.
+
 ```rust
 // 0.4
 asset_server.load("models/foo.glb");
@@ -266,19 +272,23 @@ fn some_system(
 ```
 
 ### Cameras
+
 `Camera3dBundle` is now known as `PerspectiveCameraBundle`, and `Camera2dBundle` is now known as `OrthographicCameraBundle`.
 
 `OrthographicCameraBundle` does not implement `Default`, so to change its transform at spawn while keeping everything else the same, consider something like the following:
+
 ```rust
 let mut camera = OrthographicCameraBundle::new_2d();
 camera.transform = Transform::from_translation(Vec3::new(0.0, 0.0, 5.0));
 commands.spawn_bundle(camera);
 ```
 
 ### Render API changes
+
 `RasterizationStateDescriptor` no longer exists.  Much of its functionality has been moved to other fields on `PipelineDescriptor`.  `cull_mode`, for example, is now found in the `primitive: PrimitiveState` field.
 
 Buffers of type `Vec<Color>` can no longer be uploaded to the GPU directly due to limitations with `RenderResources` and the new `Byteable` requirement.  Consider using a `Vec<Vec4>` instead, and inserting colors with `as_rgba_f32()` and `.into()` instead:
+
 ```rust
 #[derive(RenderResources, Default, TypeUuid)]
 struct SomeShader {
@@ -292,6 +302,7 @@ fn add_some_color(shader: SomeShader, color: Color) {
 ```
 
 ### Shaders should now use `CameraViewProj`
+
 The `ViewProj` matrix is now set via the name `CameraViewProj` rather than `Camera`.  If you don't update this, bevy will fail silently and you won't be able to see anything!
 
 ```glsl
@@ -307,8 +318,8 @@ layout(set = 0, binding = 0) uniform CameraViewProj {
 ```
 
 ### Diagnostics
-`PrintDiagnosticsPlugin` is now `LogDiagnosticsPlugin`.
 
+`PrintDiagnosticsPlugin` is now `LogDiagnosticsPlugin`.
 
 ### System Ordering
 

content/learn/book/migration-guides/0.5-0.6/_index.md

@@ -284,7 +284,7 @@ This was done to accommodate the new [`SystemState`] which allows easier cached
 
 ### Vector casting functions are now named to match return type
 
-The casting functions for [`IVec2`], [`DVec2`], [`UVec2`], and [`Vec2`] have all been changed from being named after their inner elements' cast target to what the entire "Vec" is being casted into. This affects all the different dimensions of the math vectors (i.e., [`Vec2`], [`Vec3` ]and [`Vec4`]).
+The casting functions for [`IVec2`], [`DVec2`], [`UVec2`], and [`Vec2`] have all been changed from being named after their inner elements' cast target to what the entire "Vec" is being casted into. This affects all the different dimensions of the math vectors (i.e., [`Vec2`], [`Vec3`] and [`Vec4`]).
 
 ```rust
 // 0.5
@@ -343,7 +343,8 @@ SpriteBundle {
 [`SpriteBundle`]: https://docs.rs/bevy/0.6.0/bevy/sprite/struct.SpriteBundle.html
 [`Sprite`]: https://docs.rs/bevy/0.6.0/bevy/sprite/struct.Sprite.html
 
-### Visible is now Visibility 
+### Visible is now Visibility
+
 The [`Visible`] struct, which is used in a number of components to set visibility, was renamed to [`Visibility`]. Additionally, the field `is_transparent` was removed from the struct. For 3D, transparency can be set using the `alpha_mode` field on a material. Transparency is now automatically enabled for all objects in 2D.
 
 ```rust