I wasn't aware of this until I saw it here -- I was just about to add in a request for rich text formatting. I think as part of onboarding the user it'd be good to mention that the app supports markdown and provide the user with a template to use as a guide (in the off chance the person using is not familiar with markdown). It may also be good to include visual rich text formatting for those who want a more familiar and user-friendly guide on editing their notes.