Update discord badge

Author: jeromewu

README.md

@@ -32,7 +32,7 @@ Check next steps of ffmpeg.wasm [HERE](https://github.com/ffmpegwasm/ffmpeg.wasm
 
 Join us on Discord!
 
-![Discord Banner 2](https://discordapp.com/api/guilds/1017664732561424404/widget.png?style=banner2)
+[![Discord](https://dcbadge.vercel.app/api/server/NjGMaqqfm5)](https://discord.gg/NjGMaqqfm5)
 
 ## Installation