title: Add a header to wkhtmltoimage
body: <p>I am trying to add some text the top of an html image using wkhtmltoimage. I am not sure if I am using the right argument. At the moment, I am failing with...</p>
  
  <p><code>wkhtmltoimage --custom-header helloworld http://www.google.com google.png</code></p>
  
  <p>The <a href="http://madalgo.au.dk/~jakobt/wkhtmltoxdoc/wkhtmltoimage_0.10.0_rc2-doc.html" rel="nofollow">help file</a> suggests I need a value after the text. It is not clear to me what this represents. I also would like to add more than one word (e.g. <code>hello world</code>). Is this possible?</p>