Update Android README dev instructions (#2814)

Updated the Dev Setup instructions for Android

kotlin/android/README.md

@@ -6,12 +6,52 @@ locally.
 ## Dev Setup
 
 1. [Install Rust](https://www.rust-lang.org/tools/install)
+
 1. [Install Android Studio](https://developer.android.com/studio)
+
 1. Install your JDK 17 of choice. We recommend just
    [updating your CLI](https://stackoverflow.com/questions/43211282/using-jdk-that-is-bundled-inside-android-studio-as-java-home-on-mac)
    environment to use the JDK bundled in Android Studio to ensure you're using
    the same JDK on the CLI as Android Studio.
+
+1. Install the Android SDK through Android Studio.
+   * Open Android studio, go to Android Studio > Preferences
+   * Search for `sdk`
+   * Find the `Android SDK` nav item under `System Settings` and select
+   * Click the `Edit` button next to the `Android SDK Location` field
+   * Follow the steps presented to install Android SDK
+
+1. Install `NDK` using Android Studio
+
+   To see which version is installed, make sure to select the `Show Package Details` checkbox in the `Android SDK` settings page in Android Studio
+
+   ![Android SDK Tools](./images/android-studio-sdk-tools.png)
+
+   Make sure the correct NDK version is installed by looking at: `../../rust/connlib/clients/android/connlib/build.gradle.kts`
+
+1. Set the following ENV variables in the start up config for your shell:
+   ```
+   JAVA_HOME=/Applications/Android\ Studio.app/Contents/jbr/Contents/Home
+   ANDROID_HOME=/Users/<username>/Library/Android/sdk
+   NDK_HOME=$ANDROID_HOME/ndk-bundle
+   PATH=$PATH:$ANDROID_HOME/platform-tools:$ANDROID_HOME/tools:$ANDROID_HOME/tools/bin
+   ```
+1. Make sure the following Rust targets are installed:
+   ```
+   aarch64-linux-android
+   arm-linux-androideabi
+   armv7-linux-androideabi
+   i686-linux-android
+   x86_64-linux-android
+   ```
+
+   If using `rustup` you can run:
+   ```
+   rustup target add aarch64-linux-android arm-linux-androideabi armv7-linux-androideabi i686-linux-android x86_64-linux-android
+   ```
+
 1. Perform a test build: `./gradlew assembleDebug`
+
 1. Add your debug signing key's SHA256 fingerprint to the portal's
    [`assetlinks.json`](../../elixir/apps/web/priv/static/.well-known/assetlinks.json)
    file. This is required for the App Links to successfully intercept the Auth