Improve SQLiteSession documentation with a runnable async example

[MuhammadAbdullah95]

This update improves the SQLiteSession usage example in the documentation by making it a fully runnable script.
Changes include:

• Wrapped async calls inside an async def main() function.
• Used asyncio.run() for proper async execution.
• Added if __name__ == "__main__": guard for clarity.
• Added comments to guide users and make the snippet beginner-friendly.

This makes it easier for developers (especially those new to async in Python) to run and understand the example without additional setup.

[seratch]

Thanks for sending this. However, we'd like to avoid repeatedly having main function for all code snippets in the page.