Ask HN: What platform/tool do you use for user documentation (knowledge base)?

We're planning to publish some user documentation (non-technical) for a SaaS app. We don't want to host it ourselves. Looking for a platform that is:

- CMS-based (can publish/edit/delete articles without the need for a git commit, for example)

- Can map to a 'custom domain'

- Cheap or free (to start with)

Suggestions would be appreciated.