There's a bit of a trick thing here in golf.
There is a rule that says you can't give advice to other players. Would a note containing advice, or a recommendation for a club, be against the rules? Yes.
There may be some clause in the rules of Augusta that covers notes as well. I'm not sure on that. I don't think the USGA has a rule including notes.
Here's where I find it tricky ...
You are standing on the tee box with your competitors and you can hear them talking...IE:
"It's 275 to the front, 280 to the flag, wind is from the left. I'd call it a 3w." Everyone on the box just heard what that guy is hitting. While it's not advice, it's no secret. Hell, you can look at club most of the time and tell what a guy is hitting.