I don't have enough reputation here to leave comments, so I'll have to leave them as part of an answer, but I would note, from my own academic integrity research, that the answer isn't always clear cut.
On the face of it, passing notes to another student sounds fine.
In practice, it depends a lot on how the notes were compiled and any additional value added.
As an example, there are sites that exist which reward students for uploading their lecture notes. They often breach the copyright of the original author (think of all the work the lecturer/professor went in to compile that course). Or, they breach the copyright of the university (since many universities automatically own the copyright of teaching materials produced by someone employed by that university). That would often result in an academic penalty based on breaching academic misconduct regulations. Deliberate breach of copyright could also result in a case that is taken through the legal system.
Now, in practice neither of those are likely to happen, but there have been several recent cases of cheating in universities being progressed in the real world, for instance, students getting someone else to take their exam for them who have ended up with a prison term.
What if the notes are edited before being shared? Well, the same copyright issues still apply. There is a point where the editing is sufficient that the notes could be considered a new piece of work, but that is a long way away.
What if the notes are being shared for free between students? The same issues still apply. A lecturer is unlikely to be concerned if it's a one-off event with a good reason (a student was ill and couldn't attend, so you supply them with a copy of the lecture notes), but a systematic activity, like constructed revision notes, may be considered unacceptable.
What then might be a good way to proceed?
One thing you might want to do is contact the lecturer and offer the edited revision notes, to be made available to all students in the class as an additional resource. Many lecturers are very happy to supply additional material that they didn't have to compile themselves.
I agree with the other comments that you can use other existing sources to supplement your knowledge, such as textbooks, MOOCs, academic papers or YouTube videos. I'd always encourage my students to do this. If nothing else, it shows a wider interest.
Some students do hire outside support. Again, this is usually okay if it is just tutorial support, with the proviso that a lot of essay mills now operate in this space, with the intention of upselling towards their other cheating services. There are other obvious areas that aren't acceptable, but do happen, for instance hiring a teaching assistant who has privileged access to the course materials.
Reviewing previous test and examination papers also sounds perfectly acceptable. In the UK, those are all expected to be available to students. It still amazes me when I hear about universities where they're not available.
University staff themselves are expected to lead the academic integrity movement by example. That includes not allowing one student to have an unfair advantage over another student (consider the example where one group of students, such as a fraternity, has compiled a test bank which students outside that group don't have access to).
By the same token, there would be an expectation that coursework questions and exam questions were not reused. Using these could be said to be encouraging students to cheat. This would be uncommon in the UK, as the culture is to write original questions and have them externally checked, but if it did happen, I'd expect it to be a disciplinary issue.
Going back to the original question, if you do share your notes, I'd recommend checking that the content hasn't changed. I certainly update my materials every time I deliver a module, sometimes quite substantially where I think that I can improve the student experience (or when it's important to include an additional concept, which generally means trimming somewhere else). That's another good reason for running the notes past the lecturer to check that the information is still current.