[sitemap] custom layout

[tripodsan]

from @davidnuescheler:

it seems that chrome doesn't have a good way to render hreflang sitemaps. i have seen some sitemap styling, and i am not sure if that's worth-while to include or if we could look at a special styling in sidekick (similar to the json viewer) on this.

[rofe]

Unfortunately this is not easy to do: unlike regular sitemaps, hreflang sitemaps do not come with a native document.body in Chrome, which prevents us from injecting the sidekick element...