docs: clarify MetadataFacade async description

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

content/docs/guides/objectql-migration.mdx

@@ -96,7 +96,7 @@ await kernel.bootstrap();
 
 ### MetadataRegistry → MetadataFacade
 
-If you were using `MetadataRegistry` from `@objectql/types`, the upstream equivalent is `MetadataFacade`. The key difference is that `MetadataFacade` methods are **async** (returns `Promise`):
+If you were using `MetadataRegistry` from `@objectql/types`, the upstream equivalent is `MetadataFacade`. The key difference is that `MetadataFacade` methods are **async**:
 
 ```diff
 - import { MetadataRegistry } from '@objectql/types';