Create namespaces “manual”, and “wiki”, with subspaces for each chapter. This can be done simply by editing the sidebar. Deciding the chapters and sections will provide the main skeleton for the whole manual, so we need to put some thinking into this before writing a single word. Once that's defined, we'll leave it “fixed”, with perhaps an annual revision as you suggested.
Populate the “wiki” namespace with the cheat sheet and other things to help writers.
Create templates for chapters, articles, one command, etc. and install them in dokuwiki
… open it up and let's start writing.