Just posting this here to suggest that this Enhancement Request could be super useful. I was able to get some support from this article
But I note the issue is set to Resolved. The answer is great - but it should be much easier to do than having to step into the HTML.
Please add your support to this request to get the ability to create a Table of Contents in a Solution Article. I hear it is on path...we just need to let Freshservice know we need it.