I don't find a mention of comments for FLASHER.INI in the Flasher User Guide. Experiments show that It seems like pretty much anything that isn't an expected section heading or setting value is ignored (and therefore could be considered a comment).
But in order to avoid problems with a future firmware update, I wonder if there is an undocumented support for an actual comment? Ini files usually use a semi-colon to introduce a comments, but sometimes a '#' is used instead. Also sometimes comments need to be on a line by themselves, but some .ini parsers support comments on the same line as a section heading or a setting.
For example: