doc: fix ESM JSON/data URL import example

PR-URL: #42728
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Beth Griggs <bgriggs@redhat.com>

doc/api/esm.md

@@ -200,7 +200,7 @@ URLs being used is:
 
 ```js
 import 'data:text/javascript,console.log("hello!");';
-import _ from 'data:application/json,"world!"';
+import _ from 'data:application/json,"world!"' assert { type: 'json' };
 ```
 
 #### `node:` Imports