Improve documentation on duration fields for StudentSchoolAttendanceEvent

This ticket is in reaction to EDFI-1908

In summary: there are two different duration fields on StudentSchoolAttendanceEvent: eventDuration and schoolAttendanceDuration. The distinction between them is not very clear in the documentation.

• eventDuration: The amount of time for the event as recognized by the school: 1 day = 1, 1/2 day = 0.5, 1/3 day = 0.33.
• schoolAttendanceDuration: The duration in minutes of the school attendance event.

I suppose the implication is that one tracks in days and the other in minutes. But why have both? Also, the latter is an integer, and the former a decimal value.

Finally, the eventDuration strangely is limited to decimal(3,2), meaning that it has a range of -9.99 to 9.99 days. Can we plainly document somewhere - whether in the MetaEd Model & Handbook, or in the Tech Docs page for the attendance domain - this range, the significance of a negative number, and what to do if you need to record 10 days or more?