Add migration guide

Author: LikeLakers2

release-content/migration-guides/bevy_reflect_reorganization.md

@@ -0,0 +1,21 @@
+---
+title: "`bevy_reflect` reorganized to de-clutter the crate root"
+pull_requests: [22342]
+---
+
+`bevy_reflect` has undergone a large reorganization. Many modules have been exposed in the crate root, each containing items relevant to their "kind" of reflected type:
+
+* `array`
+* `enums`
+* `list`
+* `map`
+* `set`
+* `structs`
+* `tuple`
+* `tuple_struct`
+
+For example, the `structs` module now contains the `Struct` trait, as well as related items like `DynamicStruct` or `StructInfo`.
+
+This change was made to de-clutter the crate root of `bevy_reflect`, hopefully making it easier to find what traits and types you need for your use of reflection.
+
+Migrating should only require editing your `use` statements. The Rust compiler will give hints at the new type paths, should you need any assistance.