Back to top

1. Add back_to_top: true and back_to_top_text: "Back to top" to the site configuration.

2. Check that a link to the top of the page appears at the bottom of each page, independently of the configuration of other footer info such as gh_edit_link.

3. Check that the text of the link changes when the value of back_to_top_text is updated in the site configuration.