title: Vim syntax highlighting for special comments
body: <p>Is there a simple way in Vim to extend the syntax highlighting for a language to allow for important comments to stand out? For instance, if a line that starts with <code>//</code> denotes a regular comment in a C file, I'd like to have lines starting with <code>//!!</code> be highlighted in a more prominent color.</p>
  
  <pre><code>// this is a regular comment - line color should be the default color for comments
  
  //!! this is an important comment - highlight line in red
  </code></pre>