Our needs are simple, so we have something† based on kramdown (in GFM mode) and tilt-pdf[0] (shameless plug) which generates a TOC, handles styles, headers/footers, and leverages wkhtmltopdf††. Documentation is in git as markdown files, linted, generated, and published as part of CI/CD. Comments/edits are done though GitLab MRs implementing an editorial review process. Occasional contributions are done through GitLab web editor, and more involved non-technical people use VSCode to sync, write, and commit. The GitLab flow of (Issue->Branch->MR)->(Fetch->Edit->Commit->Push)->(Review->Merge->Publish) is quite assisted and works quite well with open-minded non-tech people.

[0]: https://github.com/lloeki/tilt-pdf

† The tool should be open-sourced as soon as we can clean up the code of hardcoded internal stuff. It'll appear over there: https://github.com/adhoc-gti/makebook

†† Contemplating moving to headless Chrome. Also, increasingly using Hugo for online documentation.