title: Extract whatever is in brackets using regular expressions
body: <p>I really don't understand regex at all, and it hurts my head.</p>
  
  <p>I've a bit of text which looks like this</p>
  
  <pre><code>blah blah blah (here is the bit I'd like to extract)
  </code></pre>
  
  <p>...and I don't really understand how to extract this using PHP's preg_split, or equivalent, command.</p>
  
  <p>How do I do this? And where's a good place to understand how preg works?</p>