Forget to prevent send empty discord payload

just prevents the discord payload from being sent to the void...

Also in the future it is possible to make a better leaderboard, e.g. top of the week, top of the month, etc.

Content.Server/_NF/GameRule/NfAdventureRuleSystem.cs

@@ -214,6 +214,8 @@ private async Task ReportRound(String message,  int color = 0x77DDE7)
     {
         Logger.InfoS("discord", message);
         String _webhookUrl = _configurationManager.GetCVar(CCVars.DiscordLeaderboardWebhook);
+        if (_webhookUrl == string.Empty)
+            return;
 
         var payload = new WebhookPayload
         {
@@ -288,4 +290,4 @@ public EmbedFooter()
         {
         }
     }
-}
+}