docs: update changelog

apps/v4/content/docs/changelog/2026-05-registry-include.mdx

@@ -1,15 +1,22 @@
 ---
-title: May 2026 - Registry Include
-description: Organize large registries with included registry.json files.
+title: May 2026 - Registry Include and Validate
+description: Organize and validate source registries.
 date: 2026-05-20
 ---
 
-We've added support for `include` in `registry.json`.
+This release adds two updates for registry authors:
+
+- `include` for composing large source registries from multiple `registry.json`
+  files.
+- `shadcn registry validate` for checking source registries before publishing.
+
+This makes it easier to maintain source and dynamic registries without keeping
+one large `registry.json` file by hand.
 
 Registry authors can now organize a large source registry across multiple
 `registry.json` files and compose them with `shadcn build`.
 
-```txt
+```txt /registry.json/
 registry.json
 components
 └── ui
@@ -23,7 +30,7 @@ hooks
 ```
 
 {/* prettier-ignore */}
-```json title="registry.json" showLineNumbers
+```json title="registry.json" showLineNumbers {6-7}
 {
   "$schema": "https://ui.shadcn.com/schema/registry.json",
   "name": "acme",
@@ -64,6 +71,21 @@ registry metadata.
 registry, so a file declared in `components/ui/registry.json` is written as
 `components/ui/button.tsx` in the built registry item.
 
+## Validate your registry
+
+You can now validate a source registry before publishing or serving it.
+
+```bash
+npx shadcn registry validate
+```
+
+Validation runs against the source registry files directly. You do not need to
+run `shadcn build` first.
+
+The command checks the root `registry.json`, included registry files, item
+schema errors, duplicate item names, include rules, and local item file paths.
+Validation reports all actionable errors it can find in one run.
+
 ## Registry loaders
 
 The `shadcn/registry` package also exports `loadRegistry` and