Project Management Governance

I am relatively new to the PM role at my organization. One of the tasks my manager would like to tackle in the near future is to create a Governance document. This would be the place of all PM truth. Not only do I envision it holding all the important information about workfront and how our team uses it, training, tracking time, license types, etc. but it would also give a breakdown of our resource allocation process in terms of “rules of engagement,” when it comes to how we accept projects, how we say no, the metrics we use to base that decision on - clear cut guidelines that are standard across the board, triggers that indicate that we need to outsource, etc. If this, then that. Do any of your organizations currently use that sort of documentation or have resources you can share that might help me get started in creating one for mine? I have yet to find anything even within Workfront documentation to truly cover that side of my goal and I'm not sure where to begin.