If group name is empty, use directory name

internal/config/v1.go

@@ -69,6 +69,9 @@ func (z *ZurgConfigV1) GetGroupMap() map[string][]string {
 
 	// Populate the groupMap and groupOrderMap
 	for directory, val := range z.Directories {
+		if val.Group == "" {
+			val.Group = directory
+		}
 		groupMap[val.Group] = append(groupMap[val.Group], directory)
 		groupOrderMap[directory] = val.GroupOrder
 	}