Site templates are configured in etc/config/site-templates.conf.
The configuration format is Template Name=Godbolt.org full link.
To create a site template:
Below are instructions to generate site templates. Because it's a bit hacky feel free to not run the script, we can do so when a PR is made.
Site template screenshots are generated with a hacky script located at etc/scripts/generate_site_template_screenshots.js.
To run the script, cd to the etc/scripts/ directory and run
npm i puppeteer --no-save && node generate_site_template_screenshots.js
The script uses puppeteer and chrome to generate screenshots. The script will take a little while to run as it generates multiple screenshots per template and gives pages ample time to load.
Screenshots are located in views/resources/template_screenshots/. The script won't regenerate everything by default, to regenerate delete the screenshot images you want deleted.