docs: change slack invitation link (#7897)

README.md

@@ -26,6 +26,7 @@
 [![Commit activity](https://img.shields.io/github/commit-activity/m/apache/apisix)](https://github.com/apache/apisix/graphs/commit-activity)
 [![Average time to resolve an issue](http://isitmaintained.com/badge/resolution/apache/apisix.svg)](http://isitmaintained.com/project/apache/apisix "Average time to resolve an issue")
 [![Percentage of issues still open](http://isitmaintained.com/badge/open/apache/apisix.svg)](http://isitmaintained.com/project/apache/apisix "Percentage of issues still open")
+[![Slack](https://badgen.net/badge/Slack/Join%20Apache%20APISIX?icon=slack)](https://apisix.apache.org/slack)
 
 **Apache APISIX** is a dynamic, real-time, high-performance API Gateway.
 
@@ -43,7 +44,7 @@ The technical architecture of Apache APISIX:
 
 - Mailing List: Mail to [email protected], follow the reply to subscribe to the mailing list.
 - QQ Group - 552030619, 781365357
-- Slack Workspace - [invitation link](https://join.slack.com/t/the-asf/shared_invite/zt-1egxjz7lw-lWl142XNDopj4FlqNMUM5g) (Please open an [issue](https://apisix.apache.org/docs/general/submit-issue) if this link is expired), and then join the #apisix channel (Channels -> Browse channels -> search for "apisix").
+- Slack Workspace - [invitation link](https://apisix.apache.org/slack) (Please open an [issue](https://apisix.apache.org/docs/general/submit-issue) if this link is expired), and then join the #apisix channel (Channels -> Browse channels -> search for "apisix").
 - ![Twitter Follow](https://img.shields.io/twitter/follow/ApacheAPISIX?style=social) - follow and interact with us using hashtag `#ApacheAPISIX`
 - [Documentation](https://apisix.apache.org/docs/)
 - [Discussions](https://github.com/apache/apisix/discussions)