update donwloader docs

docs/source/guide/downloader.rst

@@ -21,7 +21,7 @@ This provides all the neccesary functionalities and backends for accessing the C
 Next to this, create a configuration file (JSON file) that contains all the data specification for 
 the data you would like to request, example:
 
-.. code-block:: JSON 
+.. code-block:: json-object 
     {
         "product_type": "reanalysis", 
         "variable": [