Consider dropping the entire section on AC meetings

[hober]

As (perhaps obliquely) suggested by @reidmore-online in a comment on #1084, maybe the Process document doesn't need to define what an AC meeting is, or require that or how they happen.

One argument for this that comes to mind: the Process document does not say anything at all about an annual technical plenary, and yet we can see that the Team has diligently organized one every year for twenty four years and counting. (A different conclusion that you could come to from this same argument is #1095.)