Ensure frontmatter is consistent

...ring/architecture/design-documents/activity_pub/_index.md

..._context_management/decisions/001_policy_on_the_client.md

...eering/architecture/design-documents/ai_gateway/_index.md

...-documents/ai_gateway/decisions/001_direct_connections.md

...ecture/design-documents/ai_gateway/decisions/002_proxy.md

...ineering/architecture/design-documents/autoflow/_index.md

.../architecture/design-documents/autoflow/relation_to_ci.md

...rchitecture/design-documents/backup_and_restore/_index.md

...hitecture/design-documents/backup_and_restore/glossary.md

...eering/architecture/design-documents/bundle_uri/_index.md

...architecture/design-documents/capacity_planning/_index.md

...ering/architecture/design-documents/cdot_orders/_index.md

...chitecture/design-documents/cdot_plan_managment/_index.md

...engineering/architecture/design-documents/cells/_index.md

...esign-documents/cells/decisions/001_routing_technology.md

...ign-documents/cells/decisions/002_gcp_project_boundary.md

...ocuments/cells/decisions/003_num_gke_clusters_per_cell.md

...design-documents/cells/decisions/004_vpc_subnet_design.md

...s/cells/decisions/005_flexible_reference_architectures.md

...gn-documents/cells/decisions/006_disaster_recovery_geo.md