fix: Updated Flutter Push Notification configuration

Author: tyllark

src/fragments/lib/push-notifications/common/getting_started/cross-platform-prereq.mdx

@@ -45,11 +45,24 @@ If you prefer using the plugins DSL, you should add the `plugins` block to the v
 </InlineFilter>
 
 <InlineFilter filters={['flutter']}>
-
-The Firebase documentation directs you to add the Google services plugin to your app `settings.gradle` using the [Gradle plugins DSL](https://docs.gradle.org/current/userguide/plugins.html#sec:plugins_block). However, we recommend you continue to use the [Legacy Plugin Application](https://docs.gradle.org/current/userguide/plugins.html#sec:old_plugin_application) instead:
-
-```groovy
-id "com.google.gms.google-services" version "4.3.14" apply false
+1. Open `android/settings.gradle.kts` and add the Google Services plugin:
+```diff title="android/settings.gradle.kts"
+plugins {
+    id("dev.flutter.flutter-plugin-loader") version "1.0.0"
+    id("com.android.application") version "8.1.0" apply false
+    id("org.jetbrains.kotlin.android") version "1.9.10" apply false
++   id("com.google.gms.google-services") version "4.3.14" apply false
+}
+```
+2. Open `android/app/build.gradle.kts` and add the Google Services plugin:
+```diff title="android/app/build.gradle.kts"
+plugins {
+    id("com.android.application")
+    id("kotlin-android")
+    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
+    id("dev.flutter.flutter-gradle-plugin")
++   id("com.google.gms.google-services")
+}
 ```
 
 </InlineFilter>