title: How to encoding utf8 in yii2
body: <p>I am learning yii2, I have issue for display utf8 in page main.php 
  this is error.</p>
  
  <pre><code>LO?I S?N PH?M
  </code></pre>
  
  <p>I have used </p>
  
  <pre><code>header('Content-Type: text/html; charset=utf-8');
  </code></pre>
  
  <p>but issue is not solved</p>
  
  <p>Please help me fix it. </p>
  
  <p>Thank you so much</p>