Init the architecture files organization

architecture/admin-gui.md

architecture/admin-tools.md

architecture/api-gateway.md

architecture/cms.md

architecture/monitoring.md

architecture/services/authentication.md

architecture/services/csv-catalog-downloader.md

architecture/services/elasticsearch/elasticsearch.md

architecture/services/elasticsearch/indexer.md

architecture/services/legacy-auth-middleware.md

architecture/services/mail.md

architecture/services/media-library.md

architecture/services/organizations.md

architecture/services/resources.md

architecture/web-app.md