update sponsor content

README.md

@@ -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>
 

README_zh.md

@@ -12,7 +12,7 @@ frp 是一个专注于内网穿透的高性能的反向代理应用，支持 TCP
 
 <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>