Where is the website source code stored?

I’d like to request that

be converted into (and ideally, start work on converting it into) a table. However, I’ve been unable to locate the source code for the website.

The source code for that page is here: content/tutorials/ImageFormats · testing · Infrastructure / gimp-web · GitLab

I found it through here: GIMP Developer - Contributing to the main website: www.gimp.org. If you want to contribute to the website probably that should be a first read.