If the author of the article is here, do try out org-mode. That is exactly what you need. It is designed to be a simple text file format, but tooling on top of it (simple editor plugins, mostly in emacs, but there are equivalent plugins in vim/neovim; I'm sure there must be something in today's kool-aid VSCode editors) make it so so much more powerful.
Org-mode has TODOs, Agendas, tables, nested/collapsible headings, mind-maps etc. You can also generate richly formatted PDFs/HTML/DOC files as well.
Org-mode has TODOs, Agendas, tables, nested/collapsible headings, mind-maps etc. You can also generate richly formatted PDFs/HTML/DOC files as well.