PR Summary

This adds documentation to add a "triage team" to our organization as discussed on today's call. The purpose of this is to:

• provide a low barrier to formally recognize users as contributing to the maintenance of Matplotlib (by giving them power and responsibility)
• empower more people to help where they are willing and able
• to incentive more people to triage issues
• (secondary) provide a ramp / pipeline to contributing PRs (and reviewing PRs!) for new contributors

This text is based on https://scikit-learn.org/dev/developers/bug_triaging.html and modified to better fit Matplotlib.

Task that need to be done immediately outside of a PR if we merge this:

• create triage_team in the github ACL system (I think only me @dopplershift and @efiring can currently do that?) with triage rights on matplotlib/matplotlib

If this catches on we may want to:

• add more formal method of requesting to join (ex a form), but for now while we figure out if this is even a good idea, lets keep it informal.
• add "triage team captain" or similar to the named roles in the governance docs, but again lets see if this catches on / is a good idea before we do that.

On the call I suggested 1 triage would be the threshold to be invited, but ended up with 2-3 just so that we have a bit more context to evaluate. Being optomistic, I expect most of these requests / nominations to be fulfilled.

sklearn has a slightly higher bar for inviting people to the triage team (https://scikit-learn.org/dev/governance.html#triage-team) and more ceremony, but I would rather have this be broader and less formal.

We can deal with bad-faith actors if they come up and I expect a vast majority of the issues we will have will be miss-labeled or miss-milestoned issues which are almost trivially fixable.