docs: rename news to news_list

Make it better name.

Author: kenjis

user_guide_src/source/tutorial/news_section/003.php

@@ -10,7 +10,7 @@ public function index()
     {
         $model = model(NewsModel::class);
 
-        $data['news'] = $model->getNews();
+        $data['news_list'] = $model->getNews();
     }
 
     public function show($slug = null)

user_guide_src/source/tutorial/news_section/004.php

@@ -11,8 +11,8 @@ public function index()
         $model = model(NewsModel::class);
 
         $data = [
-            'news'  => $model->getNews(),
-            'title' => 'News archive',
+            'news_list' => $model->getNews(),
+            'title'     => 'News archive',
         ];
 
         return view('templates/header', $data)

user_guide_src/source/tutorial/news_section/005.php

@@ -1,8 +1,8 @@
 <h2><?= esc($title) ?></h2>
 
-<?php if ($news !== []): ?>
+<?php if ($news_list !== []): ?>
 
-    <?php foreach ($news as $news_item): ?>
+    <?php foreach ($news_list as $news_item): ?>
 
         <h3><?= esc($news_item['title']) ?></h3>