docs: enhance README with centered banner and improved layout

- Added a centered banner image to the README for better visual appeal.
- Updated the layout to improve readability and presentation of project information.

README.md

@@ -1,6 +1,14 @@
+<div align="center">
+<a href="https://tapdata.io/">
+<img src="./assets/tapdata-banner.jpg" width="900px"/>
+</a>
+<br/><br/>
+
 [![Release](https://img.shields.io/github/v/tag/tapdata/tapflow.svg?sort=semver)](https://github.com/tapdata/tapflow/releases)
 [![PyPI Downloads](https://static.pepy.tech/badge/tapflow)](https://pepy.tech/projects/tapflow)
 
+</div>
+
 ## What is TapFlow
 
 TapFlow is a newly launched programming API framework for the TapData Live Data Platform. It allows developers and data engineers to build data pipelines and models using a simple powerful programming language.