Update OpenGitOps project governance to reflect GitOps WG merging

[scottrigby]

The GitOps Working Group is merging into the OpenGitOps project. This has been discussed for a long time, and was recently agreed upon unanimously in Slack that it's the right time to do this.

Maintainer reviews and merging of this PR to project Governance and related files constitutes the official merge. See https://github.com/open-gitops/project/blob/merge-gitops-wg-into-opengitops/GOVERNANCE.md for a preview.

To-do

• [x] update the wg meeting documents to point to open gitops
  • see OpenGitOps project meetings doc
• [x] make a decision on the wg-gitops slack channel
  • the decision has been made to move from #wg-gitops to #opengitops slack channel
• [x] follow-up: point slack to #opengitops (or vice versa and rename)
  • There is an open CNCF Service Desk ticket to do that pending this PR being merged https://cncfservicedesk.atlassian.net/servicedesk/customer/portal/1/CNCFSD-2204
• [ ] follow-up: update project home page with current status:
  • [ ] https://github.com/open-gitops
  • [ ] https://opengitops.dev
• [ ] follow-up: present to TAG App Delivery in May/June with an update on project status

Additional info

• Currently this PR does not remove Chairs. This could be done in this PR if desired by Maintainers or as a future follow-up.
• for previous history see: https://github.com/open-gitops/project/pull/123

[JaimeMagiera]

lgtm

[williamcaban]

/lgtm

[scottrigby]

With @williamcaban 's lgtm we have a supermajority of maintainers 🎉 Nice work everyone. The WG succeeded. Excited for the future of OpenGitOps 😄