You should take a look at Notion.so. I'm using it personally to manage my code/snippets, how-tos, and pretty much all of my knowledgebase management. It's become my second brain. With my team, we collaborate on Notion Kanban boards for project management, document collaboration, and since our company uses G-Suites, I'm using an unofficial integration (via Zappier and notion-automations.com) to import our google docs into customized notion databases to improve discovery/access (less searching, more doing) - Notion's databases support multiple views for databases: Table, List, Gallery, Calendar, Kanban, and Timeline views. Documents we collaborate on live on a notion "page" where we can @comment inline or on the overall document using a comments tool a the top of every document. We also have a Slack integration that notifies users in slack channels when there's a comment on a document or database they're following or something is assigned to them. Block creation, text/code/snippet formatting are done using markdown. Notion has integrations with Trello, Miro, Gdocs, MS Excel, Word, and others. They are working on an API to enable more customization and integrations. Most important, you are not locked into their ecosystem. If you ever decide to leave Notion, you can export all of your content in markdown, pdf, and html.
I agree, Notion is super easy to use yet powerful tool. You can write directly in markdown and code snippets have syntax highlighting.
Thanks for your advice (and to Marc as well). I have tried Notion a little bit and was very impressed by its interface, but we never got into it for real. Maybe this is a good reason to give it a try.