Implement the single-page asciidoc.org site

Develop the single-page asciidoc.org site based on the design provided by Ura Design.

This issue entails:

• Create an extension for the SSG (11ty) to convert AsciiDoc content to HTML
• Implement the responsive design in HTML/CSS/JS based on the comp/wireframes provided by Ura Design (desktop and mobile) (see #1 (closed))
• Incorporate the content into the design, using AsciiDoc where possible (see #2 (closed))
• Implement an interactive "Try It Now" feature based on Asciidoctor.js
• Test the site to make sure it works with modern desktop web browsers (Edge, Chrome, Safari 14, Firefox)