I've made a very simple plugin for your minecraft server which makes it possible for you to add your discord server invite link to it.

How to use:

Use: "/setdiscord <discord link>" to add your discord invite link.
Use: "/discord" to see the current invite link.

Permissions:

Default users won't have access to /setdiscord. All Operators can use it, if you want other users to have the permission. Here's the node to add it to your permission manager: "discord.setdiscord".

Good luck!