[Typo]: Missing underscore in unstable_ViewTransition import

### Summary

The `unstable_ViewTransition` import is missing an underscore in the first code block on the ViewTransition page.

### Page

https://react.dev/reference/react/ViewTransition

### Details

It should be

```js
import { unstable_ViewTransition as ViewTransition } from 'react';
```

instead of

```js
import { unstableViewTransition as ViewTransition } from 'react';
```