Table of Contents
What
The Table of Contents (TOC) for a page is this case refers not just to a list of all headings at the top of the page but an interactive list that has local links allowing users to quickly jump to the selected section.
Why
The TOC is one of the best places to start building good documentation. When a user reads your docs, they want to get to the information they need as quickly as possible. Within a single page, you could be covering multiple topics. A thoughtfully laid out TOC will allow a user to quickly jump to the section they need.
And building the TOC itself will lead you as an author to writing your documents in an easier-to-consume manner. More on that in the TOC Drive Docs page.
How
Most cloud-based and server-based documentation systems have built-in TOC macros.
If you are writing Markdown within a lightweight code editor like VS Code or Sublime, there are a number of plugins available that can help generate TOCs.