Docs: Correct @return type for WP_Block_Parser::parse().

This affects:
* `WP_Block_Parser::parse()`
* `WP_Block_Parser::$output`

Both the method and the property are documented as returning `WP_Block_Parser_Block[]` (an array of `WP_Block_Parser_Block` objects), but the result is in fact an array of arrays of various values, so `array[]` is the correct notation.

Follow-up to [43751] for the 5.0 branch, [44116] for trunk.

Props Chouby.
Fixes #56581.

git-svn-id: https://develop.svn.wordpress.org/trunk@54194 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-block-parser.php

@@ -191,7 +191,7 @@ class WP_Block_Parser {
 	 * List of parsed blocks
 	 *
 	 * @since 5.0.0
-	 * @var WP_Block_Parser_Block[]
+	 * @var array[]
 	 */
 	public $output;
 
@@ -221,7 +221,7 @@ class WP_Block_Parser {
 	 * @since 5.0.0
 	 *
 	 * @param string $document Input document being parsed.
-	 * @return WP_Block_Parser_Block[]
+	 * @return array[]
 	 */
 	function parse( $document ) {
 		$this->document    = $document;