Add details about required scopes for Self-Hosted Runner

[martindevnow]

Why:

When building our self-hosted runners, we encountered the requirement of the admin:org scope rather late in our development process. If we had seen this sooner, it would have raised concerns from our security team at a time that would have given us opportunity to discuss implications and work arounds.

What's being changed:

The high level documentation that outlines which scopes are required is presented up front without needing to dig through the REST API documentation to understand what scopes need to be applied to the Personal Access Token that registers the self-hosted runners.

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• I have reviewed my changes in staging (look for "Automatically generated comment" and click Modified to view your latest changes).
• For content changes, I have completed the self-review checklist.

Writer impact (This section is for GitHub staff members only):

• This pull request impacts the contribution experience
  • I have added the 'writer impact' label
  • I have added a description and/or a video demo of the changes below (e.g. a "before and after video")

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Content directory changes

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Source	Preview	Production	What Changed
content/actions/hosting-your-own-runners/autoscaling-with-self-hosted-runners.md	Modified	Original

[ramyaparimi]

@martindevnow
Thanks for opening a PR 👍 Please fill out "why" and "what's being changed" in the pull request template in the top comment in this pull request, so I can get this up for review!

[martindevnow]

@martindevnow Thanks for opening a PR 👍 Please fill out "why" and "what's being changed" in the pull request template in the top comment in this pull request, so I can get this up for review!

Thank you! I have updated the PR comments to reflect this change being proposed.

[ramyaparimi]

@martindevnow
Thanks so much for filling out the PR template! I'll get this triaged for review ⚡

[lucascosti]

Thanks a lot for this addition, @martindevnow!

Yep, you are right, we should have the org requirement here too. I made a slight change to link to the scopes explanation instead of an API operation.

We're currently in the middle of a deployment freeze at the moment, but I will mark this as ready to merge when the freeze is lifted.

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