Allow the double bracket [[Some other note filename]] notation for linking to other notes. The example here would then open the note named 'Some other note filename' when clicked.
Optionally, you could allow for linking to other notes using a word in a sentence. Hard to describe, here is an example instead.
This sentence should [[link | Some other note filename]] to a different note.
Where the word 'link' is to become the clickable text, and when clicked will open the note named 'Some other note filename'.
Hope that all makes sense, Metanota is a really nice app, I have used quite a number of note taking apps, and I really like the simplicity instilled in Metanota. I am a bit concerned about release schedules though. It seems that Metanota is not all to active. I understand that it may not be your 9-5 so to speak, but maybe once and awhile post an update about whats coming, or whats in the works if time between releases is extended. Especially for those considering purchasing the 'Pro' version, it would be nice to see activity.s Just a suggestion!