autocorrect of the -- symbol

when typing in notes, the symbol -- keeps getting auto replaced with— . This is annoying, as i like to type up linux commands or scripts in notes. Is there anything i can do to stop this? I cannot learn the symbol in the dictionary, as that only does words. I also tried going in to keyboard settings, text tab, and adding -- in to the replace/with section, without success. Interestingly i can type it in to a browser like this, but not the notes app.