Document the comma append trick for entity:save (#6104)

* Set log message during entity:save

* Document appending comm

src/Commands/core/EntityCommands.php

@@ -91,7 +91,9 @@ public function doDelete(string $entity_type, array $ids): void
     }
 
     /**
-     * Re-save entities, and publish/unpublish as specified.
+     * Re-save entities, and publish/unpublish is specified.
+     *
+     * If passing in a file with an ID in each line, append a comma to each row.
      */
     #[CLI\Command(name: self::SAVE, aliases: ['esav', 'entity-save'])]
     #[CLI\Argument(name: 'entity_type', description: 'An entity machine name.')]