Move Committees outside of the Governance doc

[murillodigital]

Committees are continuously changing whereas governance likely pretty much set once agreed upon, lets move committees into their own .md

[murillodigital]

Should also add a bullet as to how to volunteer for a comittee

[scottrigby]

Good idea. Do you mind making a note on this pr about that? https://github.com/gitops-working-group/gitops-working-group/pull/125?

Also cross-linking the open PR on contributing open-gitops/gitops-working-group#88 @alisondy and I can connect with about how to tag-team work on these two PRs 😺