default discord message by current Channel & a few fixes

Pilz.Updating.Administration/Discord/DiscordBotConfig.cs

@@ -1,4 +1,5 @@
-using System;
+using Newtonsoft.Json;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -9,9 +10,25 @@ namespace Pilz.Updating.Administration.Discord
     public class DiscordBotConfig
     {
         public string DiscordBotToken { get; set; } = string.Empty;
-        public string DefaultUpdateMessage { get; set; } = string.Empty;
         public string DefaultAppName { get; set; } = string.Empty;
         public string UpdateNotificationRoll { get; set; } = string.Empty;
         public bool UseProxy { get; set; } = true;
+        public Dictionary<Channels, string> DefaultUpdateMessages { get; } = new()
+        {
+            { Channels.Stable, null },
+            { Channels.PreRelease, null },
+            { Channels.Beta, null },
+            { Channels.Alpha, null }
+        };
+
+        [JsonProperty, Obsolete]
+        private string DefaultUpdateMessage
+        {
+            set
+            {
+                foreach (var keys in DefaultUpdateMessages.Keys)
+                    DefaultUpdateMessages[keys] = value;
+            }
+        }
     }
 }