Update community Slack link

.template-helpers/get-help.md

@@ -1 +1 @@
-[the Docker Community Slack](https://dockr.ly/slack), [Server Fault](https://serverfault.com/help/on-topic), [Unix & Linux](https://unix.stackexchange.com/help/on-topic), or [Stack Overflow](https://stackoverflow.com/help/on-topic)
+[the Docker Community Slack](https://dockr.ly/comm-slack), [Server Fault](https://serverfault.com/help/on-topic), [Unix & Linux](https://unix.stackexchange.com/help/on-topic), or [Stack Overflow](https://stackoverflow.com/help/on-topic)