docs: update react-native-screens section

Author: kacperkapusciak

versioned_docs/version-6.x/react-native-screens.md

@@ -8,16 +8,37 @@ Prior to `2.14.0`, all screens are essentially regular native `View` in each pla
 
 With the advent of `react-native-screens`, the native screen optimization is brought possible to React Navigation by bringing the native navigation component (`UIViewController` for iOS, and `FragmentActivity` for Android). By using `react-native-screens`, it is possible for each native platform to optimize the memory usage for screens that are under the view stack and also simplify the native node hierarchy. You can take a look at the comparison [here](https://twitter.com/janicduplessis/status/1039979591815897088?s=21) to see the performance gain.
 
+React Navigation 6 incorporates `react-native-screens` in version >=3.0.0 which means the optimizations are already enabled by default.
 ## Setup when you are using Expo
 
-By default expo already included `react-native-screens`, all you need to do is pasting the following snippet before your navigation stacks are rendered (typically in an `index.js` or `App.js` file):
+Expo SDK 41 and up comes with `react-native-screens` that works out-of-the-box without additional configuration. If you installed dependencies with `expo install` as stated in [Getting started](http://localhost:3000/docs/6.x/getting-started#installing-dependencies-into-an-expo-managed-project) section of documentation you are good to go!
 
-```js
-// Before rendering any navigation stack
-import { enableScreens } from 'react-native-screens';
-enableScreens();
+## Setup in normal react-native applications
+
+### Setup on iOS
+
+The installation of `react-native-screens` on iOS is supported by auto-linking, if you made sure the pods are installed with `pod install` in project directory, no other actions are necessary.
+
+### Setup on Android
+
+This change is required to avoid crashes related to View state being not persisted consistently across Activity restarts.
+
+You'll need to edit `MainActivity.java` which is located in `android/app/src/main/java/<your package name>/MainActivity.java` file.
+
+Add this method to the body of `MainActivity` class:
+```java
+@Override
+protected void onCreate(Bundle savedInstanceState) {
+  super.onCreate(null);
+}
 ```
 
-## Setup in normal react-native applications
+and make sure to add an import statement at the top of the file:
+
+```java
+import android.os.Bundle;
+```
+
+and that's everything!
 
-You will need to follow the installation instruction from [react-native-screens](https://github.com/software-mansion/react-native-screens) first. After that, you can import the library like mentioned above and enjoy the optimization.
+For more information consult installation instructions in [react-native-screens](https://github.com/software-mansion/react-native-screens#installation) repository.