This page is either found on /p/about/ in your fresh Cynthia install, or on https://github.com/strawmelonjuice/CynthiaCMS-JS/blob/main/README.MD.
Cynthia is a NodeJS alternative to the engine I built to host https://strawmelonjuice.com/. (The original engine is built on a mix of PHP and javascript, Cynthia is pure Javascript.)
The philosophy?
Why use a database if your content is mostly static? Why use an admin panel if you have file access?
Sure, WordPress can be useful, and can be the best way to set up your web site. But if you like thinkering about with configuration files and like writing your pages in markdown (yes, that's Cynthia's default format!), then join the Cynthia side (basically Jekyll but less... Jekyll, and no Ruby).
Unpack the latest Cynthia to your folder of choice.
See https://github.com/strawmelonjuice/CynthiaCMS-JS/blob/main/clean_slate/GETTINGSTARTED.MD.