What are some alternatives?
Dr.Explain - Dr.Explain software is a help file authoring tool.
MadCap Flare - Documentation for Any Audience, Language or Format
Confluence - Confluence is content collaboration software that changes how modern teams work
Zmags - Zmags provides solutions create and publish web experiences instantly.
Nuclino - Nuclino is a unified real-time workspace for teams that brings all your notes, tasks, and docs together in one place.
SPIP - Système de Publication pour Internet