New: Add indexer option for Discord on grab notifications

src/NzbDrone.Core/Notifications/Discord/Discord.cs

@@ -101,6 +101,10 @@ namespace NzbDrone.Core.Notifications.Discord
                         discordField.Name = "Links";
                         discordField.Value = GetLinksString(series);
                         break;
+                    case DiscordGrabFieldType.Indexer:
+                        discordField.Name = "Indexer";
+                        discordField.Value = message.Episode.Release.Indexer;
+                        break;
                 }
 
                 if (discordField.Name.IsNotNullOrWhiteSpace() && discordField.Value.IsNotNullOrWhiteSpace())

src/NzbDrone.Core/Notifications/Discord/DiscordFieldType.cs

@@ -11,7 +11,8 @@ namespace NzbDrone.Core.Notifications.Discord
         Links,
         Release,
         Poster,
-        Fanart
+        Fanart,
+        Indexer
     }
 
     public enum DiscordImportFieldType