Add instructions for new fine grained GitHub PAT

[ibizaman]

Description

Added permission setup instructions for the new fine-grained GitHub PAT.

I don't know how to show proof that the instructions work correctly since I can't link to my PAT but I tested it with this action which only succeeded after giving both permissions.

Checklist

• [ ] Tested functionality against a test repository (see "How to test changes")
• [x] Added or updated relevant documentation (leave unchecked if not applicable)