Agreed. The current docs include the “Using an _index.md” page. The current site definitely needs that page, but the new site doesn’t. For the record, I think it was a great addition, so thank you.
You might want to dig around https://hugodocs.info a bit more. It’s not just a reorganization of files or a new theme. Parts of the docs have been changed considerably. For example, the “Extras” and “Tutorials” sections have gone the way of the dodo bird.
Nevertheless, I’m glad you brought this up. I just reviewed the page for the homepage template and realized there were opportunities for improvement. I’ve already pushed them to the live site:
https://hugodocs.info/templates/homepage/#adding-content-and-front-matter-to-the-homepage
I also think I should add a similar heading and page section to the taxonomy templates page. Stay tuned.
Oh, and if you have anymore feedback, would you mind adding an issue to the Hugodocs.info GH repo or possibly replying to the following thread instead? I feel like we’re hijacking this one a bit. 
Thanks!