Trac was great years ago. As much as I know, they were stuck on Python 2 until the very last moment 3 years ago, so it became almost unusable, and the UI is not responsive even today, not usable on phone. It used to be really great, but be careful relying on it before doing research on its current development.
For technical notes, I’d recommend Sphinx docs or single reStructuredText files on a cloud storage or repository. You can create all kind of formats (PDF, HMTL, ect.) from it, and it’s future proof.