update sponsor content
@@ -17,7 +17,7 @@ frp also has a P2P connect mode.
<p align="center">
<a href="https://www.doppler.com/?utm_campaign=github_repo&utm_medium=referral&utm_content=frp&utm_source=github" target="_blank">
- <img width="300px" src="https://raw.githubusercontent.com/fatedier/frp/dev/doc/pic/sponsor_doppler.png">
+ <img width="400px" src="https://raw.githubusercontent.com/fatedier/frp/dev/doc/pic/sponsor_doppler.png">
</a>
</p>
