Hi Keith,
My opinion on this, and based on things I have seen when auditing QMSs. If the job description is used for evaluating competency, then it might make sense to have revision control. That way when the competency is evaluated, the user of that document knows it is the latest. If the job description provides guidance for job responsibilities related to "quality tasks" or leadership decision making, controlled makes sense. Of course, it also depends on your company's stance on document control.
All the best,
Jodi McMahon