Add a migration guide and release notes for short type path asset procesors.

Author: andriyDev

release-content/migration-guides/type_path_for_asset_traits.md

@@ -0,0 +1,25 @@
+---
+title: Traits `AssetLoader`, `AssetTransformer`, `AssetSaver`, and `Process` all now require `TypePath`
+pull_requests: [21339]
+---
+
+The `AssetLoader`, `AssetTransformer`, `AssetSaver`, and `Process` traits now include a super trait
+of `TypePath`. This means if you previously had a loader like:
+
+```rust
+struct MyFunkyLoader {
+    add_funk: u32,
+}
+```
+
+You will need to add the following derive:
+
+```rust
+#[derive(TypePath)]
+struct MyFunkyLoader {
+    add_funk: u32,
+}
+```
+
+`TypePath` comes from `bevy_reflect`, so libraries may also need to add a dependency on
+`bevy_reflect`.

release-content/release-notes/short_type_path_asset_processors.md

@@ -0,0 +1,44 @@
+---
+title: Short-type-path asset processors
+authors: ["@andriyDev"]
+pull_requests: [21339]
+---
+
+Asset processors allow manipulating assets at "publish-time" to convert them into a more optimal
+form when loading the data at runtime. This can either be done using a default processor, which
+processes all assets with a particular file extension, or by specifying the processor in the asset's
+meta file.
+
+In previous versions of Bevy, the processor had to be **fully** specified in the asset's meta file.
+For example:
+
+```
+(
+    meta_format_version: "1.0",
+    asset: Process(
+        processor: "bevy_asset::processor::process::LoadTransformAndSave<asset_processing::CoolTextLoader, asset_processing::CoolTextTransformer, asset_processing::CoolTextSaver>",
+        settings: (
+            loader_settings: (),
+            transformer_settings: (),
+            saver_settings: (),
+        ),
+    ),
+)
+```
+
+As you can see, processor types can be very verbose! In order to make these meta files easier to
+manipulate, we now also support using the "short type path" of the asset. This would look like:
+
+```
+(
+    meta_format_version: "1.0",
+    asset: Process(
+        processor: "LoadTransformAndSave<CoolTextLoader, CoolTextTransformer, CoolTextSaver>",
+        settings: (
+            loader_settings: (),
+            transformer_settings: (),
+            saver_settings: (),
+        ),
+    ),
+)
+```