Remove slack and update with forum link (#454)

Author: pdabelf5

README.md

@@ -19,12 +19,10 @@ and [NGINX Gateway Fabric](https://github.com/nginx/nginx-gateway-fabric) projec
 If you experience issues with this project, please [open a bug][bug] in
 GitHub. If you have any suggestions or feature requests, please [open an idea][idea] on GitHub discussions.
 
-You can contact us directly via [email protected] or on the [NGINX Community Slack][slack] in
-the `#kubernetes` channel.
+You can also get help through the [NGINX Community Forum](https://community.nginx.org).
 
 [bug]: https://github.com/nginx/telemetry-exporter/issues/new?assignees=&labels=&projects=&template=bug_report.md&title=
 [idea]: https://github.com/nginx/telemetry-exporter/discussions/categories/ideas
-[slack]: https://nginxcommunity.slack.com/channels/kubernetes
 
 ## Contributing