Need a table of content that will help a user to quickly jump to a particular section. It can be auto-generated using Atx-style headers level. But this table of content should not be present at the top but rather as a sticky or persistent sidebar. You can take Hashnode's own Support Page as a perfect example.

As you can see in the image above, Hashnode has a sticky Table of Content or Navigation section that remains at its place even when we scroll the page.