[📚] Please update onTokenChanged documentation

[maxlenker]

Documentation Feedback

Your appCheck documentation does not mention anywhere that onTokenChanged is not implemented for iOS. I'm in a very specific situation where I needed that to work and spent hours trying to figure out why I was getting that warning if it was not mentioned anywhere online that it would not work on iOS. It was not until I looked at the source code that I saw how it was implemented. I understand that you guys have constraints due to working with the official firebase SDK, but PLEASE mention things like this in the documentation

[mikehardy]

Hey there 👋 really sorry to hear you had some mis-spent time there, I always hate to hear that. I will note that there's an "edit" link at the top of every single documentation page, and if you can think of any place you'd like to see a note like that you can throw a quick PR in to the docs from the github web UI in just a few seconds, we merge doc updates all the time - users are the primary source of them