Beautiful notes! But I don't believe those figures are made using LaTeX and Vim... I can't see how you convert keyboard strokes to nice figures shown in the example.
> There, I explained my workflow of taking lecture notes in LaTeX using Vim and how I draw figures in Inkscape.
Looks like the author was using Inkscape earlier but may have switched to something else recently. You can draw impressively beautiful diagrams in LaTeX with TikZ although it can be a lot of work to do so with TikZ which would make it difficult for live note taking.