Document better how to change schedule rule rate

[SharpEdgeMarshall]

After increasing the schedule rule rate from 5 minutes to 1 hour i've found that no more snapshots were taken.

After some code digging i discovered there is a var time_delta (defaults to 4 minutes) that defines a window when the lambda function could be called to match the SnapshotTime.

To make the system works again i had to increase it to 59 minutes.
Pay attention that its value should be exactly (your_schedule_rule_rate - 1) to not incur in multiple or skipped snapshots.

I think that this should be documented more.