docs: fix incorrect explanation

The cleanRules() method controls whether to remove validation rules or not.

Author: kenjis

user_guide_src/source/models/model.rst

@@ -390,7 +390,7 @@ For many people, validating data in the model is the preferred way to ensure the
 standard, without duplicating code. The Model class provides a way to automatically have all data validated
 prior to saving to the database with the ``insert()``, ``update()``, or ``save()`` methods.
 
-.. important:: The validation in the model class only validate provided fields.
+.. important:: When you update data, the validation in the model class only validate provided fields.
     So when you set the rule ``required``, if you don't pass the required field data,
     the validation won't fail. This is to avoid validation errors when updating only some fields.