Update render.mdx

Author: vonovak

website/docs/12.x/docs/api/render.mdx

@@ -10,10 +10,10 @@ function render(
 The `render` function is the entry point for writing React Native Testing Library tests. It deeply renders the given React element and returns helpers to query the output components' structure.
 
 ```jsx
-import { render } from '@testing-library/react-native';
+import { screen, render } from '@testing-library/react-native';
 
 test('basic test', () => {
-  const screen = render(<MyApp />);
+  render(<MyApp />);
   expect(screen.getAllByRole('button', { name: 'start' })).toBeOnTheScreen();
 });
 ```