Update sidekiq concurrency setting for RPI

What does this MR do?

When we switched to Sidkiq clusters the default concurrency setting for Sidekiq was removed and replaced with a max and min setting. This changes the Raspberry Pi documentation to reflect that change

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Checklist

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Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
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Expected (please provide an explanation if not completing)

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• Documentation created/updated
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