docs: update link

Author: darkskygit

index.md

@@ -22,7 +22,7 @@ Telephone: +65 8643 9832
 
 Join our community
 
-- [Discord](https://discord.com/invite/whd5mjYqVw)
+- [Discord](https://affine.pro/redirect/discord)
 - [X.com](https://x.com/AffineOfficial)
 
 ---