dgryski/go-perfbook ? reverse-engineered prompt

Build me a clean documentation site for this Go performance book.

It should present the English version as the main reading experience, with easy links to the Spanish, Portuguese, and Chinese versions. The home page should explain that this is a practical guide to writing faster Go code, then let people jump into the table of contents and read each section smoothly. I want it to feel like a simple book site, easy to scan, with good typography, section navigation, and clear headings for topics like profiling, garbage collection, unsafe code, CGO, and advanced techniques.

Please keep it focused on reading and learning, not a flashy marketing site. Make sure the markdown content is turned into nicely formatted pages, the language versions are easy to find, and the layout works well on mobile too. If you need to look up current docs or a better way to render the markdown, go ahead and do that.