docs: Adding <Text> to avoid errors (callstack#1124)

* Adding <Text> to avoid errors

When copying the code and trying in the editor, an error is returning, demanding that the "This is a scrollable area" text be wrapped in a `<Text>` component.

* docs: importing <Text> from react-native-paper

src/components/Dialog/DialogScrollArea.js

@@ -20,7 +20,7 @@ type Props = React.ElementConfig<typeof View> & {
  * ```js
  * import * as React from 'react';
  * import { ScrollView } from 'react-native';
- * import { Dialog, Portal } from 'react-native-paper';
+ * import { Dialog, Portal, Text } from 'react-native-paper';
  *
  * export default class MyComponent extends React.Component {
  * state = {
@@ -37,7 +37,7 @@ type Props = React.ElementConfig<typeof View> & {
  * onDismiss={this._hideDialog}>
  * <Dialog.ScrollArea>
  * <ScrollView contentContainerStyle={{ paddingHorizontal: 24 }}>
- * This is a scrollable area
+ * <Text>This is a scrollable area</Text>
  * </ScrollView>
  * </Dialog.ScrollArea>
  * </Dialog>