Improve Documentation for RNN Installation

[gosha212]

Refined installation documentation

[Copilot]

Pull Request Overview

This PR refines the RNN installation documentation and updates various Android project configuration files to align with the latest requirements.

• Updated installation docs with revised Node and React Native version requirements and autolinking instructions.
• Adjusted iOS instructions to reflect changes in file editing (from AppDelegate.m to AppDelegate.h) and updated CLI commands.
• Migrated several Android components to Kotlin and updated build settings and repository configurations.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
website/docs/docs/docs-Installing.mdx	Updated installation requirements and instructions, including iOS migration details.
playground/android/build.gradle	Updated repository configurations by adding mavenCentral().
playground/android/app/src/main/java/com/reactnativenavigation/playground/MainApplication.kt	Migrated MainApplication to Kotlin with updated package registrations.
playground/android/app/src/main/java/com/reactnativenavigation/playground/MainActivity.kt	Added a Kotlin MainActivity with splash screen support.
playground/android/app/build.gradle	Added Kotlin plugin and kotlinOptions; updated dependencies.
lib/android/app/src/main/java/com/reactnativenavigation/NavigationApplication.java	Integrated new architecture entry point via DefaultNewArchitectureEntryPoint.

Comments suppressed due to low confidence (2)

website/docs/docs/docs-Installing.mdx:109

• Ensure that the change from editing AppDelegate.m to AppDelegate.h is intentional and that the migration instructions are updated accordingly to avoid confusion.

In Xcode, you will need to edit this file: `AppDelegate.h`. Its content should look like this:

playground/android/app/build.gradle:52

• [nitpick] Verify that setting the jvmTarget to '17' is consistent with the Kotlin version and project requirements, and update project documentation if necessary.

kotlinOptions { jvmTarget = '17' }

[d4vidi]

See notes