Merge branch 'docs/fix-vale-group-database' into 'master'

doc/architecture/blueprints/database_scaling/size-limits.md

doc/development/adding_database_indexes.md

doc/development/creating_enums.md

doc/development/database/avoiding_downtime_in_migrations.md

doc/development/database/background_migrations.md

doc/development/database/batched_background_migrations.md

doc/development/database/efficient_in_operator_queries.md

doc/development/database/loose_foreign_keys.md

doc/development/database/rename_database_tables.md

doc/development/database/table_partitioning.md

doc/development/database_review.md

doc/development/serializing_data.md

doc/development/verifying_database_capabilities.md