Text formatting services for documentation?

Question

Documentation

Please tell me some service where you can visually format the text (as in word) without displaying markup, with the ability to download the "source" with Markdown / ReST markup. Those services that I managed to find work on the principle of two windows. In one, the text clogged with markup is edited, in the other, the preview. Not convenient. Maybe there are services for generating documentation without the need to work with text markup?