Second this. All these fancy services are neat but hosting private data in the US is seen in Europe as a major security risk, when it's not a complete no-no. Would be cool to know about self-hosted options.
For self-hosting try https://github.com/documize/community -- WYSIWYG or Markdown, integrate data from Trello, GitHub, or roll your own integration.
Still early days yet, but you should get a feel for docs/wiki/SaaS data embedding.