Hello! It looks like you've stumbled upon the source for my personal knowledge base, a construct which I call Brain. You can explore it by following this link.
All original content is contained in the vault directory, which I write using the excellent application Obsidian (seriously, if you haven't already, go check it out). Everytime I push a change or an addition to this vault, every page gets converted into single HTML files and pushed into the gh-pages branch which is hosted on GitHub Pages. More about how this is done here.