If you are ordered to attend, they will give you a court slip to have signed. Not all groups will sign court slips--it is a matter for each group's "group conscience" whether to do so. Many will.
I suppose if they will sign court slips, you could make one up for yourself that says, _____ attended the following AA meeting __________ (name of group) _______ (date) _____ (time) __________________ (chairperson).
It doesn't hurt to have something like that to show the court. You will most likely be ordered to attend, anyway, as part of any probation or pretrial diversionary program.