The Graphene theme is an open-source, community-based effort. Continuing along that spirit, we have created a documentation wiki that multiple editors and contributors can contribute to and maintain. This allows us to better create and maintain the documentation more effectively.
The documentation wiki contains comprehensive description and explanation of the various features and options that the theme offers, as well as more advanced topics of extensive theme customisation.
If you are new to the theme, it is worth it to give the documentation a cursory reading to inform yourselves of the various features and options of the theme. This will help you make full use of the theme and explore its potential for your site.
And if you find some bits of content that are outdated or imprecise, feel free to register an account on the wiki and edit the content yourself.