Add a governance.md doc

[aterrel]

It's not clear who owns this repo or is in charge of maintaining it. Most issues are very old and I'm getting pinged about things. I can clean things up to a degree but would rather have a clear owner.

[mikofski]

Hi Andy, there is a DISC subcommittee that nominal owns it. @arliss-NF can tell you. This was started ages ago by @Dr-G then was silent for years until 2 years ago when it was rebooted and moved to Jupyter books. It is not dead imho

[aterrel]

Well just take the issue of reviewing PRs. @Dr-G hasn't contributed to this repo in 4 years. @arliss-NF hasn't ever worked on the repo but rather organized the steering committee. When I look through the list of reviewers, it's all folks who are more NF board types rather than folks who can maintain the code.

I'm going to create a maintainers group that can at least fix the broken links, update github workflows and do the maintenance tasks required to keep the resource up.

[aterrel]

Okay I've created @numfocus/discover-cookbook-maintainers but this contributing guide seems to indicate that @numfocus/disc-steering-committee should be reviewing issues. I'll draft up a governance placeholder in a few days and hopefully outline a bit more how to support this resource.