Don't show help in the TOC

[hwalinga]

If you open help and rerun the script to make the TOC, the help will be Incorporated in the TOC. That shouldn't happen:

I. Keyboard shortcuts
II. Command Mode (press Esc to enable)
III. Edit Mode (press Enter to enable)

[kmahelona]

We could update the JQuery selector to only select headings in the actual notebook. I’ll have to spin up a notebook and see what the latest looks like.