docs: fix blob callout

Author: smarroufin

docs/content/2.usage/3.blob.md

@@ -52,7 +52,7 @@ export default eventHandler(async (event) => {
 
 Returns the blob's raw data and sets `Content-Type` and `Content-Length` headers.
 
-::callout{icon="i-heroicons-information-circle"}
+::callout{icon="i-heroicons-information-circle" class="prose-code:bg-gray-50 dark:prose-code:bg-gray-800"}
 If you are fetching an image with a server route similar to the one above, you might simply want to use it this way:
 <br>
 ```vue