I found myself wanting to read the Javascript section in one go after opening the first few entries, so I did:

  u="https://raw.githubusercontent.com/jbranchaud/til/master/"; curl "${u}README.md" | sed -e '/### JavaScript/,/### /!d;//d' | awk -F'[()]' '{print $2}' | xargs -n1 -I{} curl "$u{}" >> til-javascript.md