docs(cloud_firestore_odm_generator): ODM generator now require create_per_field_to_json: true (#11728)

Author: gmarizy

packages/cloud_firestore_odm/README.md

@@ -74,10 +74,10 @@ flutter pub add --dev cloud_firestore_odm_generator
 flutter pub add --dev json_serializable
 ```
 
-## 5. Enable `create_field_map` of `json_serializable`
+## 5. Enable `create_field_map` and `create_per_field_to_json` of `json_serializable`
 
 
-For the ODM to work, it is necessary to enable the `create_field_map` of `json_serializable`.  
+For the ODM to work, it is necessary to enable the `create_field_map` and `create_per_field_to_json` of `json_serializable`.  
 This can be done by creating a `build.yaml` file next to your `pubspec.yaml` and
 paste the following:
 
@@ -88,15 +88,16 @@ targets:
       json_serializable:
         options:
           create_field_map: true
+          create_per_field_to_json: true
 ```
 
 
-This will enable `create_field_map` for the entire project.
+This will enable `create_field_map` and `create_per_field_to_json` for the entire project.
 
 Alternatively, you can enable the option on a per-model basis using `json_annotation`'s `@JsonSerializable` object:
 
 ```dart
-@JsonSerializable(createFieldMap: true)
+@JsonSerializable(createFieldMap: true, createPerFieldToJson: true)
 @Collection<Model>(...)
 class MyModel {...}
 ```