Doc updates and minor cleanup of unused resources

[hubeadmin]

Description

• Adds documentation to link off to grafana-operator-libsonnet, thanks to @DeanBrunt @nickgooding 🎉
• Removes unused openshift-ci documentation
  • We've switched to github-ci since, and we are no longer using these files

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• This change requires a documentation update
• I have added tests that prove my fix is effective or that my feature works
• I have added a test case that will be used to verify my changes
• Verified independently on a cluster by reviewer

Verification steps

NA

[NissesSenap]

LGTM