Update logo in readme, support Github dark mode
-<p align="center" >
- <a href="https://shenyu.apache.org/"><img src="https://shenyu.apache.org/img/logo/apache-shenyu.png" width="45%"></a>
-</p>
+![Light Logo](https://raw.githubusercontent.com/apache/incubator-shenyu-website/main/static/img/logo-light.svg#gh-dark-mode-only)
+![Dark Logo](https://raw.githubusercontent.com/apache/incubator-shenyu-website/main/static/img/logo.svg#gh-light-mode-only)
+
<p align="center">
<strong>Scalable, High Performance, Responsive API Gateway Solution for all MicroServices</strong>
</p>
