[feat]: document permissions for gh-pages

[ioggstream]

I expect

• gh-action template to have permissions: read-all
• gh-action template to have commented

permissions:
  # Uncomment for commiting on gh-pages.
  # content: write
  
  # Uncomment for calling gh APIs on (e.g. issues/pull-request).
  # issues: write
  # pull-requests: write