[Steven Mitchell (smitch5777)]

• Document the full _redo_type value set, including final sale, and that matching ignores case, spaces, underscores, and hyphens
• Document __final_sale_coverage as a final sale signal, and that tags are ignored entirely when _redo_type is present
• Say to send one coverage line item, and that separate items are each billed on their own price
• Note that an unrecognized _redo_type is treated as returns coverage
• Correct the final sale fallback: it also applies when every Redo purchase is final sale, and requires an enabled shipping country