This isn't enough information. You have to actually walk the user through the change and what they need to do. Spell it out. For example:

Pages no longer automatically add a `ui-body-*` class. If you want to keep the same styling as before, you can manually add the appropriate class to the markup.

```html
<div data-role="page" class="ui-body-a">
    ....
</div>
```