[Feature Request] Use relative path for attachments/pictures

[Jackson-Nickk]

Currently when attaching a picture into a note, the plain text link of it looks like this:

![Title](PictureName.jpg)

And OpenNote searches the default image folder to find the picture using its name. But let's say you sync your OpenNote folder to your PC and want to open your notes in another editor, the editor doesn't know where's the default image folder, and the link present in your markdown file generated by OpenNotes doesn't tell you where the image is, just gives a name.

I suggest OpenNote to use relative path for linking images to notes:

![Title](Images/PictureName.jpg)

So that other markdown editors can search for the image file in the specified directory relative to the notes folder repository.