Ask HN: Open source Style guides, SOPs, structures, procedures, etc.

I have recently started a new company and realised that we are also putting in processes for all the devs. Thing such as style guides, branching/git processes, code reviews, documentation requirements, project structures (we use Django for our web app), etc.

Is there any open source resource where people put all of these procedures/guides and/or where they can discuss these things?