moved communications guidelines from governance, updated and clarified process

[story645]

There's been an open issue for a while to move the communications guidelines out of the governance repository because it should function more like code or documentation guidelines. In that issue the move was waiting on a new development repo, but I figure as an incremental step it can be moved into the development guidelines section with the other documents that are more geared towards maintainers because maintainers are the audience it is currently written for. I broke up this change into:

1. move over file and add to index, closes Move the communication guidelines to the (future) development guide repo governance#24
2. update the guidelines with current info, supercedes Update comms guidelines governance#36
3. guidelines for changing guidelines, inline with the API guidance, supercedes comm lead should review changes to guidlines governance#31
4. update the release guide to use the communications channels listed in the comms guide
5. removed the checklist code from the pr-guideline b/c I made it a class in 4.

attn: @matplotlib/steering-council

[story645]

@timhoffm made all the changes and keep running into instances where it'd be really convenient to be able to cross ref the list of our communications channels 😅

[timhoffm]

I‘ve fixed some formatting.

Anybody can merge after CI pass. @story645 do you want to keep the individual commits or can we squash?

[story645]

do you want to keep the individual commits or can we squash?

I'd rather keep them separate here b/c they're all doing different things - but I'll rebase your fixes so it's cleaner. (basically I remembered/learned how to reorder commits)

[story645]

Also once this gets merged, the comms guide needs to get deleted in governance, but do we add a redirect (and if so where?)

[timhoffm]

Also once this gets merged, the comms guide needs to get deleted in governance, but do we add a redirect (and if so where?)

IMHO a redirect is not necessary. I don’t think the comma guide is something that many people have referenced. Also, redirects are nice for usability but not a strict requirement.

[story645]

I don’t think the comma guide is something that many people have referenced

I send it to people but I think I've always used the repo