Send Periodic emails about unanswered question

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Currently there is following option in settings:

Send periodic reminders about unanswered questions NOTE: in order to use this feature, it is necessary to run the management command "send_unanswered_question_reminders" (for example, via a cron job - with an appropriate frequency)

Default value: False

It would be a great help if someone could give bit detail example on how I set it up this in cron job.