Note Ruby incompability with Jekyll for GitHub Pages (#44809)

Co-authored-by: Ben Ahmady <32935794+subatoi@users.noreply.github.com>

Author: david-kudlacek

content/pages/setting-up-a-github-pages-site-with-jekyll/testing-your-github-pages-site-locally-with-jekyll.md

@@ -54,6 +54,8 @@ Before you can use Jekyll to test a site, you must:
    >
    >   To fix the error, try running `bundle add webrick`, then re-running `bundle exec jekyll serve`.
    >
+   >   If you've installed Ruby 3.2 or later, you may see other errors related to missing gems and methods, due to compatibility issues with the `github-pages` gem. In this event, you should install Ruby 3.1.x or earlier instead.
+   >
    > * If your `_config.yml` file's `baseurl` field contains your GitHub repository's link, you can use the following command when building locally to ignore that value and serve the site on `localhost:4000/`:
    >
    >   ```shell