Enhance README with MaixCam 2 Kickstarter link

Updated README to promote MaixCam 2 Kickstarter campaign.

Author: Zepan

README.md

@@ -5,7 +5,9 @@ MaixPy (v4)
 
 ![](https://wiki.sipeed.com/maixpy/static/image/maixpy_banner.png)
 
-**Let's Sipeed up, Maximize AI's power!**
+[![Back MaixCam 2 on Kickstarter](https://img.shields.io/badge/Kickstarter-Back%20MaixCam%202-05CE78?style=for-the-badge&logo=kickstarter&logoColor=white)](https://www.kickstarter.com/projects/zepan/maixcam2-build-your-next-gen-4k-ai-camera)
+
+**🚀 [MaixCam 2 is LIVE: Build Your Next-Gen 4K AI Camera!](https://www.kickstarter.com/projects/zepan/maixcam2-build-your-next-gen-4k-ai-camera) 🚀**
 
 **MaixPy** (v4): Easily create AI projects with Python on edge device