Updated overview and content organization

Dockerfile

docs/administration/admin-tools.md

docs/architecture/index.md

docs/components/indexers/editorial-content.md

docs/components/indexers/metadata-and-data.md

docs/components/off-the-shelf-apps/api-gateway.md

docs/components/off-the-shelf-apps/cms.md

docs/components/off-the-shelf-apps/elasticsearch.md

docs/components/services/authentication.md

docs/components/services/csv-catalog-downloader.md

docs/components/services/legacy-auth-middleware.md

docs/components/services/mail.md

docs/components/services/media-library.md

docs/components/services/organizations.md

docs/components/services/resources.md

docs/components/specific-apps/admin-gui.md

docs/components/specific-apps/web-app.md

docs/monitoring/monitoring.md

docs/overview/index.md

mkdocs.yml