document the new behavior

README.rst

@@ -950,6 +950,18 @@ in ``settings.py``::
 
     ZYTE_API_PROVIDER_PARAMS = {"geolocation": "IE"}
 
+When ``ZYTE_API_PROVIDER_PARAMS`` setting includes one of the Zyte API
+extraction options (e.g. ``productOptions`` for ``product``), but the
+final Zyte API request doesn't include the corresponding data type, the
+unused options are automatically removed. So, it's safe to use
+``ZYTE_API_PROVIDER_PARAMS`` to set the default options for various extraction
+types, e.g.::
+
+    ZYTE_API_PROVIDER_PARAMS = {
+        "productOptions": {"extractFrom": "httpResponseBody"},
+        "productNavigationOptions": {"extractFrom": "httpResponseBody"},
+    }
+
 Note that the built-in ``scrapy_poet.page_input_providers.ItemProvider`` has a
 priority of 2000, so when you have page objects producing
 ``zyte_common_items.Product`` items you should use higher values for