Add section on behaviour of values prop in combination with defaultValues prop (#1069)

* Add section on behaviour of values and defaultValues.mdx

* Update useform.mdx

* Update src/content/docs/useform.mdx

---------

Co-authored-by: Beier (Bill) <bluebill1049@hotmail.com>

Author: maurer2

src/content/docs/useform.mdx

@@ -170,7 +170,8 @@ useForm({
 
 ---
 
-The `values` props will react to changes and update the form values, which is useful when your form needs to be updated by external state or server data.
+The `values` prop will react to changes and update the form values, which is useful when your form needs to be updated by external state or server data. The `values` prop will overwrite the `defaultValues` prop, unless `resetOptions: { keepDefaultValues: true }` is also set for `useForm`.
+
 
 ```javascript copy
 // set default value sync