[Android] Update README for instructions (#789)

* [Android] Update README for instructions

* Update download instruction

README.md

@@ -255,20 +255,35 @@ Now, follow the app's UI guidelines to pick the model and tokenizer files from t
 
 ### Deploy and run on Android
 
-**This section is copied from the original REAMDE and may require additional integration work**
+#### Approach 1: Android Studio
 
-Please refer to our [tutorial on how to build an Android app running
-your PyTorch models with
-Executorch](https://pytorch.org/executorch/main/llm/llama-demo-android.html)
-to for an example on how to run your torchchat models on Android.
+If you have Android Studio set up, and you have Java 17 and Android SDK 34 configured, you can follow this step.
 
-![Screenshot](https://pytorch.org/executorch/main/_static/img/android_llama_app.png
- "Android app running Llama model")
+The torchchat app skeleton is located at `android/Torchchat`. Use Android Studio to open this directory.
 
-Detailed step by step in conjunction with ET Android build, to run on
-simulator for Android. `scripts/android_example.sh` for running a
-model on an Android simulator (on Mac), and in `docs/Android.md`.
+You may notice that the project is missing a file `app/libs/executorch.aar`. Please download our prebuilt archive.
 
+[executorch-llama.aar](https://ossci-android.s3.us-west-1.amazonaws.com/executorch/release/0.2/executorch-llama.aar) (SHASUM: 09d17f7bc59589b581e45bb49511d19196d0297d)
+
+```
+curl https://ossci-android.s3.us-west-1.amazonaws.com/executorch/release/0.2/executorch-llama.aar -o android/Torchchat/app/libs/executorch.aar
+echo "09d17f7bc59589b581e45bb49511d19196d0297d  android/Torchchat/app/libs/executorch.aar" | shasum --check
+```
+
+Then, click the Play button (^R) to launch it to emulator/device.
+
+Now, follow the app's UI guidelines to pick the model and tokenizer files from the local filesystem and issue a prompt.
+
+<img src="https://pytorch.org/executorch/main/_static/img/android_llama_app.png" width="600" alt="Android app running a LlaMA model">
+
+#### Approach 2: E2E Script
+
+Alternatively, you can run `scripts/android_example.sh` which sets up Java, Android SDK Manager, Android SDK, Android emulator, builds the app, and launches it for you.
+
+```
+export TORCHCHAT_ROOT=$(pwd)
+sh scripts/android_example.sh
+```
 
 
 ### Eval