Update docs with GitHub token scope for import

What does this MR do and why?

• Only repo is needed for the repo, but it appears that collaborators are different
• See https://docs.github.com/rest/collaborators/collaborators#list-repository-collaborators

  You must authenticate using an access token with the read:org and repo scopes with push access to use this endpoint.

How to set up and validate locally

• Perform a GitHub import of a project using our documentation here
• Without the read:org scope: failures (403 - Resource not accessible by personal access token)
• With the read:org scope: works

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.