Seems that - regarding what you want to achieve (the WHAT) - you are basically describing a wiki. Just that you focussed on the HOW instead of the what and ended up with something that basically no forum user apart from devs would be able to use (Git, pull requests etc.). So why not simply use a wiki? As a collaborative platform with history (that can be reverted to), rights management, annotations and background discussions or comments etc. etc. exists and works provenly in countless variants from Mediawiki to Dokuwiki for 25 years. Why reinvent the wheel and why this time in square form instead of round?