It all just makes far more since when each Note has a fileName.
Though we don't save the fileName in the YAML header. It seems quite
redundant to do that.
Another advantage of this is that if we can read any file ending with a
'.md' in a git repo. It doesn't need to be named exactly how we want it,
and we will still save the details correctly.
For this journaling app, even though we are treating journal entries as
notes, we don't really any 'id'. Just the filename is quite adequate. In
the future, we can figure out this 'id' nonsense, and if it is even
required given that we're always going to be built on top of a FS.
