Link to EssentialsX's MaxMind license tutorial

src/main/java/fr/xephi/authme/settings/properties/ProtectionSettings.java

@@ -21,7 +21,9 @@ public final class ProtectionSettings implements SettingsHolder {
         newProperty("Protection.enableProtectionRegistered", true);
 
     @Comment({"The MaxMind clientId used to download the GeoIp database,",
-        "get one at https://www.maxmind.com/en/accounts/current/license-key"})
+        "get one at https://www.maxmind.com/en/accounts/current/license-key",
+        "The EssentialsX project has a very useful tutorial on how to generate",
+        "the license key: https://essentialsx.cf/wiki/GeoIP.html"})
     public static final Property<String> MAXMIND_API_CLIENT_ID =
         newProperty("Protection.geoIpDatabase.clientId", "");