Fix Platform API example

Fix SafeAreaView style

Author: akkadaya

docs/platform.md

@@ -13,7 +13,7 @@ import {SafeAreaView, SafeAreaProvider} from 'react-native-safe-area-context';
 const App = () => {
   return (
     <SafeAreaProvider>
-      <SafeAreaView>
+      <SafeAreaView style={{ flex: 1 }}>
         <ScrollView contentContainerStyle={styles.container}>
           <Text>OS</Text>
           <Text style={styles.value}>{Platform.OS}</Text>