docs: revise readme docs about nested params (#527)

Author: stainless-app[bot]

README.md

@@ -396,7 +396,7 @@ CardCreateParams params = CardCreateParams.builder()
     .build();
 ```
 
-These can be accessed on the built object later using the `_additionalHeaders()`, `_additionalQueryParams()`, and `_additionalBodyProperties()` methods. You can also set undocumented parameters on nested headers, query params, or body classes using the `putAdditionalProperty` method. These properties can be accessed on the built object later using the `_additionalProperties()` method.
+These can be accessed on the built object later using the `_additionalHeaders()`, `_additionalQueryParams()`, and `_additionalBodyProperties()` methods.
 
 To set a documented parameter or property to an undocumented or not yet supported _value_, pass a [`JsonValue`](lithic-java-core/src/main/kotlin/com/lithic/api/core/JsonValue.kt) object to its setter: