Small change to formatting.

product_docs/docs/mongo_data_adapter/5/06_features_of_mongo_fdw.mdx

@@ -97,13 +97,13 @@ Steps for retrieving the document:
     (2 rows)
     ```
 
-### Accessing nested fields
+## Accessing nested fields
 
 MongoDB Foreign Data Wrapper allows you to access individual fields within nested JSON documents by mapping the nested structure to columns in a foreign table. 
 This works by mapping the nested structure of the MongoDB document to relational columns in the foreign table definition, using dot notation (key2.subkey21) to reference nested fields.
 You can retrieve these fields from a collection as shown in the following example:
 
-#### Example
+### Example
 
 ```text
 db1> db.test_sub_json.find()