title: nbconvert use '--allow-chromium-download'
body: <p>I tried downloading a Jupyter Notebook as pdf by clicking on <code>File</code> -&gt; <code>Download as</code> -&gt; <code>Pdf</code> via pyppeteer. I get the below error while doing so:</p>
  <pre><code>nbconvert failed: No suitable chromium executable found on the system. Please use '--allow-chromium-download' to allow downloading one.
  </code></pre>
  <p>I had installed pyppeteer using command <code>conda install -c conda-forge pyppeteer</code> . Now I am trying to download the pdf via Jupyter GUI but it fails.</p>
  <p>How can I do that ? And do I need to run some Command on anaconda terminal to do it?</p>