docs: do not show unrelated code in sample code

Author: kenjis

user_guide_src/source/tutorial/news_section.rst

@@ -88,6 +88,7 @@ some additional tools to make working with data simpler. Add the
 following code to your model.
 
 .. literalinclude:: news_section/002.php
+    :lines: 11-18
 
 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

@@ -1,7 +1,13 @@
 <?php
 
+namespace App\Models;
+
+use CodeIgniter\Model;
+
 class NewsModel extends Model
 {
+    protected $table = 'news';
+
     public function getNews($slug = false)
     {
         if ($slug === false) {