Put visibility info closer to decision info

[felicitymay]

Why:

Fixes: #2418

The current documentation on creating a new repository for your GitHub Pages site explained that only public repositories were supported for free accounts, but this was in the header information for the topic and not where people were making a decision about repository visibility.

What's being changed:

I've made the following changes:

1. Moved the existing warning about privacy to the section about setting up GitHub Pages for an existing repository.
2. Revised the introduction to the section on creating a new repository for GitHub Pages to remind users with GitHub Free and GitHub Free for organizations accounts to create a public repository.

You can see the impact of these changes here:

• Staging site with revisions: GitHub.com and GitHub Enterprise Server 3.0
• Live site with current page: https://docs.github.com/en/github/working-with-github-pages/creating-a-github-pages-site#creating-a-repository-for-your-site

Check off the following:

• I have reviewed my changes in staging. (look for the deploy-to-heroku link in your pull request, then click View deployment)
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[felicitymay]

Now that the staging site is deployed, I've updated the PR summary to include links to the live and staging versions of the topic affected to make it easier to review.

[lecoursen]

Let me know if you have any questions!

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours.

[aleksandrpidgurskij]

Y mi neznayt