Add README.md (#2249)

examples/python-chat-app/README.md

+# Ollama Chat App
+
+Build a Llama2 chat app using Streamlit and Ollama.
+
+## Running the Example
+
+1. Ensure you have the `llama2` model installed:
+
+   ```bash
+   ollama pull llama2
+   ```
+2. Install the Python Requirements.
+
+   ```bash
+   pip install -r requirements.txt
+   ```
+3. Run the example:
+
+   ```bash
+   python main.py
+   ```