Nice doc series. Perhaps consider linking your lines documentation in the todo docs as an example of how to shift items around? Every time vimwiki/todo.txt comes up here people bring up how to move/delete completed items, often because they're unaware of :move and friends.
Note: Your .vimrc link in configuration¹ is broken.
Edit: After re-reading my comment it sounds like a complaint, it wasn't meant that way and I hope it didn't come across that way. I did enjoy reading your series!