New: (Cardigann) - Cardigann v4 Support for categorydesc

based on Jackett 02e43bd6a9838562a14c6bd6ea10cfed5a293d59
based on Jackett 60d2c425e1038a28f54bda658a9f543f3a197a66

Fixes #782

src/NzbDrone.Core/Indexers/Definitions/Cardigann/CardigannParser.cs

@@ -464,6 +464,22 @@ namespace NzbDrone.Core.Indexers.Cardigann
                         }
                     }
 
+                    value = release.Categories.ToString();
+                    break;
+                case "categorydesc":
+                    var catsDesc = MapTrackerCatDescToNewznab(value);
+                    if (catsDesc.Any())
+                    {
+                        if (release.Categories == null || fieldModifiers.Contains("noappend"))
+                        {
+                            release.Categories = catsDesc;
+                        }
+                        else
+                        {
+                            release.Categories = release.Categories.Union(catsDesc).ToList();
+                        }
+                    }
+
                     value = release.Categories.ToString();
                     break;
                 case "size":