Docs: Standardise the type name for booleans and integers.

This brings these docs inline with the documentation standards.

Props ravipatel, justinahinon

Fixes #51426


git-svn-id: https://develop.svn.wordpress.org/trunk@49120 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-hook.php

@@ -490,7 +490,7 @@ final class WP_Hook implements Iterator, ArrayAccess {
 	 *
 	 * @link https://www.php.net/manual/en/iterator.valid.php
 	 *
-	 * @return boolean
+	 * @return bool Whether the current position is valid.
 	 */
 	public function valid() {
 		return key( $this->callbacks ) !== null;