Change example published URL from .md to .html

While the markdown file is indeed available at that URL after publishing, I assume most users would be interested in the HTML version.

Author: AustinWise

content/github/working-with-github-pages/creating-a-github-pages-site.md

@@ -43,7 +43,7 @@ versions:
 
 ### Next steps
 
-You can add more pages to your site by creating more new files. Each file will be available on your site in the same directory structure as your publishing source. For example, if the publishing source for your project site is the `gh-pages` branch, and you create a new file called `/about/contact-us.md` on the `gh-pages` branch, the file will be available at {% if currentVersion == "free-pro-team@latest" %}`https://<user>.github.io/<repository>/{% else %}`http(s)://<hostname>/pages/<username>/<repository>/{% endif %}about/contact-us.md`.
+You can add more pages to your site by creating more new files. Each file will be available on your site in the same directory structure as your publishing source. For example, if the publishing source for your project site is the `gh-pages` branch, and you create a new file called `/about/contact-us.md` on the `gh-pages` branch, the file will be available at {% if currentVersion == "free-pro-team@latest" %}`https://<user>.github.io/<repository>/{% else %}`http(s)://<hostname>/pages/<username>/<repository>/{% endif %}about/contact-us.html`.
 
 You can also add a theme to customize your site’s look and feel. For more information, see {% if currentVersion == "free-pro-team@latest" %}"[Adding a theme to your {% data variables.product.prodname_pages %} site with the theme chooser](/articles/adding-a-theme-to-your-github-pages-site-with-the-theme-chooser){% else %}"[Adding a theme to your {% data variables.product.prodname_pages %} site using Jekyll](/articles/adding-a-theme-to-your-github-pages-site-using-jekyll){% endif %}."