docs: add PHPDoc types

Author: kenjis

user_guide_src/source/tutorial/news_section.rst

@@ -98,7 +98,7 @@ some additional tools to make working with data simpler. Add the
 following code to your model.
 
 .. literalinclude:: news_section/002.php
-    :lines: 11-18
+    :lines: 11-23
 
 With this code, you can perform two different queries. You can get all
 news records, or get a news item by its slug. You might have

user_guide_src/source/tutorial/news_section/002.php

@@ -8,6 +8,11 @@ class NewsModel extends Model
 {
     protected $table = 'news';
 
+    /**
+     * @param false|string $slug
+     *
+     * @return array|null
+     */
     public function getNews($slug = false)
     {
         if ($slug === false) {