docs: describe who has access to system tables

Summary

• docs: describe who has access to system tables

Address changes from picodata@72920175

24.5.0-373-g72920175

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• Close #338 (closed)
• Cherry-pick to: 24.6 / 24.5
• Staging:
  • ~/architecture/system_tables/
  • ~/tutorial/access_control/#tables_access