Check for groups.io presence

[jeefy]

(Most) CNCF projects are expected to have a presence on cncf.groups.io. I propose a check to ensure there's at least one mailing list created that follows the pattern of cncf-{project-name}-* (ex. cncf-buildpacks or cncf-buildpacks-dev would both be valid)

There are some exceptions that we need to think about however (mainly, older/graduated projects). Kubernetes uses Google Groups, for example. So perhaps this check should be (initially) only valid on projects that have been adopted starting in 2020 and newer?

[tegioz]

Hi @jeefy 👋

Would this check be for public mailing lists or private ones as well?

(assuming it'd be for public ones..)

Doing a quick check to https://lists.cncf.io/g/main/subgroups I've seen 19 projects with a mailing list, 16 of them matching the cncf-{project-name}-* pattern. Just for reference there are 72 projects registered in CLOMonitor that were accepted after 2020-01-01, so taking the 19 as valid only ~25% of them would be passing this check as of today. Is that all right?