Ask HN: How to build a help section like this?

browsing segment.io I found the help section with a neat little search box, and what appears to be frequently asked questions.

I also noticed the same thing on cloudflare.

Wondering if there's some existing code I can use, or a provider specializing in such thing?

example: https://segment.io/help/ example: https://support.cloudflare.com/hc/en-us