Fixing explanation related to the --disableupdate

[nikola-jokic]

Why:

The documentation states that you should pass --disableupdate during the run.sh, but it will throw a warning after the runner PR is merged. --disableupdate flag should be passed during the registration phase.

Closes #16801

What's being changed:

Explanation and example when you should pass the --disableupdate

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

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  • 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")

[github-actions]

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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]

@nikola-jokic Thanks for opening a pull request! We've triaged this issue for technical review by a subject matter expert 👀

[thboop]

Hey 👋 . As a maintainer of the actions/runner I can say this is correct from a technical standpoint, but would love if someone on the docs team could review the verbiage and get this merged whenever it is convenient for y'all.

[skedwards88]

Thank you for this addition! I made some minor style suggestions that I will go ahead and incorporate, then we'll get this merged down for you.

[github-actions]

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