message: add comment for enum_generate
diff: @@ -658,6 +658,7 @@ force_class_not_simple = {
  "cv::dnn::Net", # marked as Simple, but it's actually boxed
  }
  +# set of enum's that need to be generated, other enums are just expanded to constants, elements are EnumInfo.fullname
  enum_generate = {
  ### calib3d ###
  "cv::HandEyeCalibrationMethod",
  