fix captioned image issue

Author: lennessyy

docs/encyclopedia/data-conversion/external-storage.mdx

@@ -19,6 +19,8 @@ tags:
   - Data Converters
 ---
 
+import { CaptionedImage } from '@site/src/components';
+
 The Temporal Service enforces a ~2 MB per-payload limit. When your Workflows or Activities handle data larger than this
 limit, you can use External Storage to offload payloads to an external store (such as S3) and pass a small reference
 token through the Event History instead. This is called the