message: Update CODEOWNERS to fit new org
diff: # The last matching pattern takes precedence.
  # https://help.github.com/articles/about-codeowners/
  -* @spotify/backstage-core
  -/docs/features/techdocs @spotify/techdocs-core
  -/plugins/cost-insights @spotify/silver-lining
  +* @backstage/maintainers
  +/docs/features/techdocs @backstage/techdocs-core
  +/plugins/cost-insights @backstage/silver-lining
  /plugins/cloudbuild @trivago/ebarrios
  -/plugins/techdocs @spotify/techdocs-core
  -/plugins/techdocs-backend @spotify/techdocs-core
  -/packages/techdocs-cli @spotify/techdocs-core
  -/packages/techdocs-container @spotify/techdocs-core
  -/.github/workflows/techdocs.yml @spotify/techdocs-core
  -/.github/workflows/techdocs-pypi.yml @spotify/techdocs-core
  -/.changeset/cost-insights-* @spotify/silver-lining
  +/plugins/techdocs @backstage/techdocs-core
  +/plugins/techdocs-backend @backstage/techdocs-core
  +/packages/techdocs-cli @backstage/techdocs-core
  +/packages/techdocs-container @backstage/techdocs-core
  +/.github/workflows/techdocs.yml @backstage/techdocs-core
  +/.github/workflows/techdocs-pypi.yml @backstage/techdocs-core
  +/.changeset/cost-insights-* @backstage/silver-lining
  