Yes, the note only exists on your computer, but it is inserted into
the page. That means, the possibilities a note has are (more or less)
limited to what a website is allowed do. And websites cannot access
local files in your computer.
Maybe there is *some* way, as an add-on has more privileges, but I
don't know how (and there are other features/issues I'd consider as
more important at the moment, so I cannot spend time on this, sorry).