title: How to change label text of the ActiveField?
body: <p>I have created new Yii2 basic project and want to dig in.</p>
  
  <p>There is a Username field on login page:
  <img src="https://i.stack.imgur.com/Vn5Gj.png" alt="enter image description here"></p>
  
  <p>I want to change label 'Username' to a custom one, e.g. 'My superb label'.
  I have read the manual:
  <a href="http://www.yiiframework.com/doc-2.0/yii-widgets-activefield.html" rel="noreferrer">http://www.yiiframework.com/doc-2.0/yii-widgets-activefield.html</a></p>
  
  <p>After investigating a little I've got the next result:
  <img src="https://i.stack.imgur.com/Yy2uF.png" alt="enter image description here"></p>
  
  <p>I have changed only template and it has changed the layout: </p>
  
  <pre><code>&lt;?= $form-&gt;field($model, 'username', [
      "template" =&gt; "&lt;label&gt; My superb label &lt;/label&gt;\n{input}\n{hint}\n{error}"
  ])?&gt;
  </code></pre>
  
  <p>How to change the text of the label in a correct way?
  What is best practice?</p>