README: Add reminder/info about limiting backup lifetime with regular backups
I've added an extra paragraph to the README.md to aid with limiting the keep time of backups when setting up a regular backup schedule.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
I've added an extra paragraph to the README.md to aid with limiting the keep time of backups when setting up a regular backup schedule.