Add note about Redis prefixes in provisioning docs

What does this MR do?

Adds clarification about using different Redis prefixes depending on Reference Architectures type.

Related issues

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gl-quality/get-maintainers:

• Merge request:
  • Merge Request Title and Description are up to date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
• Code:
  • Documentation created/updated in the same MR.