title: Add mandatory(*) for labelText in Input Decoration in Flutter
body: <p>I want to add asteric sign in <code>InputDecoration</code> labelText and change color(like red) of it so that user understand easily this field is required.</p>
  
  <pre class="lang-dart prettyprint-override"><code>TextField(
      autofocus: true,
      controller: _nameCtrlr,
      keyboardType: TextInputType.text,
      decoration: InputDecoration(
      labelText: "Name *",
     ))
  </code></pre>
  
  <p>Expected result like this image
  <a href="https://i.stack.imgur.com/dMOJ4.png" rel="nofollow noreferrer">Sample Image</a></p>