I agree, some guidelines are needed. I recall the manual has some of them already: https://github.com/nethesis/nethserver-docs/blob/master/README.rst#editing-guidelines
About the editor: the GitHub one is online and immediately available. No docutils/git installation needed. Thus I liked it and pointed as the general tool to document the RST translation workflow.
Do you think it is a good tool for basing an howto on it?