title: Customize automatically generated TOC on jekyll/kramdown site
body: <p>I have a Jekyll site that uses kramdown for markdown. In <code>_config.yml</code> I have the following setting that ensures that only <code>&lt;h2&gt;</code> and <code>&lt;h3&gt;</code> elements show up in the automatically generated table of contents:</p>
  
  <pre><code>kramdown: 
    toc_levels: "2,3" 
  </code></pre>
  
  <p>This works fine, but on some pages I would like to include <code>&lt;h4&gt;</code> elements in the TOC as well, while retaining the existing <code>&lt;h2&gt;</code> and <code>&lt;h3&gt;</code> configuration on other pages. Is this possible?</p>
  
  <p>On any page I can access the <code>_config.yml</code> definitions like this:</p>
  
  <pre><code>{{ site.kramdown.toc_levels }} 
  </code></pre>
  
  <p>Is there a way to <em>set</em> the value of the <code>toc_levels</code> on a page?</p>