Replace references to cron.update_migration_post_id with cron.update_migration_poster_id in docs (#11068)
Across several files, references to cron.update_migration_post_id are made, although the actual setting is called cron.update_migration_poster_id according to modules/setting/cron.go (10e2f29144/modules/setting/cron.go (L54)).
Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>