Update README.md and add model optimization sample (#426)

Author: EmmaNingMS

mobile/examples/phi-3/android/README.md

@@ -1,12 +1,13 @@
-# ONNX Runtime Mobile Phi-3 Android sample application with ORT GenAI library support
+# Local Chatbot on Android with Phi-3, ONNX Runtime Mobile and ONNX Runtime Generate() API
 
 ## Overview
 
-This is a basic [Phi-3](https://huggingface.co/microsoft/Phi-3-mini-4k-instruct-onnx) example application for [ONNX Runtime](https://github.com/microsoft/onnxruntime) on Android with [Ort-GenAI](https://github.com/microsoft/onnxruntime-genai) support for running generative AI models. This app demonstrates the usage of phi-3 model in a simple question answering chatbot mode.
+This is a basic [Phi-3](https://huggingface.co/microsoft/Phi-3-mini-4k-instruct) Android example application with [ONNX Runtime mobile](https://onnxruntime.ai/docs/tutorials/mobile/) and [ONNX Runtime Generate() API](https://github.com/microsoft/onnxruntime-genai) with support for efficiently running generative AI models. This app demonstrates the usage of phi-3 model in a simple question answering chatbot mode.
 
 ### Model
-The model used here is from the source: [HuggingFace](https://huggingface.co/microsoft/Phi-3-mini-4k-instruct-onnx#phi-3-mini-4k-instruct-onnx-models)
-and optimized for int4 CPU and Mobile usage.
+The model used here is [ONNX Phi-3 model on HuggingFace](https://huggingface.co/microsoft/Phi-3-mini-4k-instruct-onnx/tree/main/cpu_and_mobile/cpu-int4-rtn-block-32-acc-level-4) with INT4 quantization and optimizations for mobile usage.
+
+You can also optimize your fine-tuned PyTorch Phi-3 model for mobile usage following this example [Phi3 optimization with Olive](https://github.com/microsoft/Olive/tree/main/examples/phi3). 
 
 ### Requirements
 - Android Studio Giraffe | 2022.3.1 or later (installed on Mac/Windows/Linux)