Draft PR and testing governance policy

[graphitefriction]

In order to alleviate a lot of cognitive overhead, let's write down the guidelines we've been applying and/or want to apply when managing pull requests and feature testing in some of the projects in the Asciidoctor organization. This should improve consistency and transparency. First, @mojavelinux wants to sort the guidelines that apply to Core versus, for example, Asciidoctor Epub. Also, we've kicked around the following project terms and their meanings which may or may not help with this issue:

Run = Lead
Assist = Partner
Coordinate = Mediate
Support = Laissez-Faire

This draft doesn't have cover all the scenarios. First, let's just get down what we've been doing that we want to keep doing.

This document will be stored in the new policies component that will, for now, be stored in this repository since it won't be a versioned document.

[graphitefriction]

Materials for reference:

• https://www.mozilla.org/en-US/about/governance/policies/module-ownership/
• https://www.softwaretestingnews.co.uk/open-source-governance-accelerates-innovation/
• http://nerdstein.net/blog/community-governance-considerations-open-source-projects
• https://opensource.guide/leadership-and-governance/
• https://opensource.com/open-organization/18/4/new-governance-model-research
• https://github.com/moby/moby/blob/master/CONTRIBUTING.md
• https://gist.github.com/calebamiles/c578f88403b2fcb203deb5c9ef941d98
• https://github.com/rust-lang/rfcs
• https://jenkins.io/project/governance/
• https://github.com/nodejs/TSC/blob/master/Project-Lifecycle.md