fix(docs): Use bracket syntax for admonition titles

Admonitions with custom titles must use bracket syntax per
remark-directive specification.

docs/docs/guides/developer-guide/database-entity/index.mdx

@@ -39,7 +39,7 @@ class ProductReview extends VendureEntity {
 }
 ```
 
-:::caution TypeScript ES2022+ Compatibility
+:::caution[TypeScript ES2022+ Compatibility]
 If your `tsconfig.json` uses `"target": "ES2022"` or later (including **Node.js v24+**), you **must** also set `"useDefineForClassFields": false`.
 
 Without this setting, ES2022 class field semantics cause entity fields to be overwritten with `undefined` after the constructor runs, resulting in "null value in column violates not-null constraint" database errors.

docs/docs/guides/extending-the-dashboard/customizing-pages/customizing-detail-pages.mdx

@@ -7,7 +7,7 @@ customize any existing detail page in the Dashboard.
 
 ## Custom form inputs
 
-:::warning Custom Fields
+:::warning[Custom Fields]
 This feature replaces inputs for **built-in entity fields** only (like `name`, `description`, `slug`).
 
 To customize the form input for a **custom field** you defined in your plugin, use the [Custom Field Components](/guides/extending-the-dashboard/custom-form-components/#custom-field-components) instead.