Feature request

Feature description:

Currently the server full message cannot be as easily changed without needing a language file, regardless of changing it in spigot.yml. What the plugin should do is grab the message from spigot.yml first, and if the file/key is null, it can use the Server full locale message as a fallback (for compatibility with CraftBukkit servers)

How the feature is useful:

This would reduce confusion on why the spigot.yml's server full message isn't working

Closed with #3899

Disable use-custom-server-full-message to use bukkit's default message