GC-1466/adds self mailer qr codes documentation

[juanfriss]

Fixes GC-1466

• Updates QR code documentation to include self mailers (apart from letters and postcards).
• Updates pages to: Specify the pages where the QR code should be stamped in a comma separated format. Your QR code can be printed in the same position on multiple pages. For postcards, the values should either be "front", "back" (for either front or back) or "front,back" (for the QR code to be printed on both sides). For self-mailers, the values should either be "inside", "outside" (for either inside or outside) or "inside,outside" (for the QR code to be printed on both sides). For letters, the values can be specific page numbers ("1", "3"), page number ranges such as "1-3", or a comma separated combination of both ("1,3,5-7").
• Updates position description to: Sets how a QR code is being positioned in the document. When using position 'relative', you should provide one of 'top' or 'bottom', and one of 'left' or 'right'.
• Updates the details description: Properties that the letters in your Creative should have. Check within in order to add a QR code to your creative.

Checklist

• Up to date with main
• All the tests are passing
  • Delete all resources created in tests
• Prettier
• Spectral Lint
• npm run bundle outputs nothing suspect
• npm run postman outputs nothing suspect

Changes

Areas of Concern (optional)