You can’t disable it by default, but I’m pretty sure you can use their formatting in notes (color and everything).
It’s all mark-up. I’ll try to find the reference.
Edit: Wait, I think that was from one of rfindley’s userscripts, actually.
Edit2: Nope, I was completely wrong, it was this userscript:
Nope
Edit3: Actually rfindley is now taking care of support (so I wasn’t that wrong)