Update readme.md

update chat link.

readme.md

@@ -222,7 +222,7 @@ go get -u github.com/zeromicro/go-zero
 
 ## 9. Chat group
 
-Join the chat via https://join.slack.com/t/go-zero/shared_invite/zt-10ruju779-BE4y6lQNB_R21samtyKTgA
+Join the chat via https://discord.gg/4JQvC5A4Fe
 
 ## 10. Cloud Native Landscape