This implementation looks correct to me, although I'm not 100% convinced the feature is valuable on the balance. If we suppose most READMEs are small and have, like, 2-3 sections (and the actual docs are, like, not in a giant README file) then I could see this getting in the way more than it helps. Your call, though; we can also see if anyone complains, or we could activate the TOC only at some threshold (like at least 5 sections).