Fix typo for $parent_instance param in RecursiveDataStructureTraverser constructor (#422)

* Fix typo for `$parent_instance` param in `RecursiveDataStructureTraverser` constructor

* Apply suggestion and reformat

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Co-authored-by: Daniel Bachhuber <[email protected]>

Author: petitphp

src/WP_CLI/Entity/RecursiveDataStructureTraverser.php

@@ -24,9 +24,9 @@ class RecursiveDataStructureTraverser {
 	/**
 	 * RecursiveDataStructureTraverser constructor.
 	 *
-	 * @param mixed $data The data to read/manipulate by reference.
-	 * @param string|int $key The key/property the data belongs to.
-	 * @param static $parent
+	 * @param mixed       $data            The data to read/manipulate by reference.
+	 * @param string|int  $key             The key/property the data belongs to.
+	 * @param static|null $parent_instance The parent instance of the traverser.
 	 */
 	public function __construct( &$data, $key = null, $parent_instance = null ) {
 		$this->data   =& $data;