Update Helm Teams with current info and links

[scottrigby]

What this PR does

• Remove Monocular
• update links to maintainers list files
• update charts maintainers description (no longer a central charts repo, but help with charts tooling and documentation)
• updates wording in governance file to match change to charts maintainers team. No material changes to governance

Open questions

1. What do we do with Helm org repos unaccounted for in the Teams list, which are also unarchived and have an existing OWNERS file?

   There are a few unarchived repos in the helm org that aren't accounted for in the list of Teams. The Teams file says:

   Repositories under the Helm organization not owned by another team, listed below, are owned by the Org Maintainers.

   However some of those repos not covered by the teams list do have OWNERS files. Does that mean those owners files override the statement about unlisted ones being owned by the Helm Org Maintainers?

   Here is the list:

   • https://github.com/helm/helm-mapkubeapis/blob/main/OWNERS
   • https://github.com/helm/helm-2to3/blob/main/OWNERS
   • https://github.com/helm/acceptance-testing/blob/main/OWNERS
   • https://github.com/helm/get-helm-sh/blob/main/OWNERS

   Should add those somewhere clearly under this list of teams, remove those old OWNERS files, or archive the repos?