Update hybrid sample readme

Author: lethargicpanda

samples/gemini-hybrid/README.md

@@ -6,8 +6,15 @@ This sample is part of the [AI Sample Catalog](../../). To build and run this sa
 
 This sample demonstrates how to use the Firebase Hybrid SDK, utilizing both on-device (Gemini Nano via [ML Kit Prompt API](https://developers.google.com/ml-kit/genai/prompt/android)) and cloud-based models via the [Firebase AI Logic SDK](https://firebase.google.com/docs/ai-logic).
 
-### Key Snippets
+The sample lets users generate generic user reviews for a hotel based on a few selected topics. 
 
+<div style="text-align: center;">
+<img width="320" alt="Gemini Hybrid SDK in action" src="gemini_hybrid.png" />
+</div>
+
+## How it works
+
+Here is how the model is instantiated to leverage hybrid inference:
 ```kotlin
 val model = Firebase.ai(backend = GenerativeBackend.googleAI())
                 .generativeModel(