title: Using packages that are not imported as part of examples in a vignette
body: <p>I am using functions from the <code>forcats</code> and <code>devtools</code> packages in a vignette for a package I am developing. I have them listed in the <code>Suggests</code> (not not <code>Imports</code>) field in the NAMESPACE file. </p>
  
  <p>When I run <code>devtools::check()</code>, the following NOTE is returned:</p>
  
  <pre><code>checking for unstated dependencies in vignettes ... NOTE
  '::' or ':::' imports not declared from:
    ‘devtools’ ‘forcats’
  </code></pre>
  
  <p>According to the answer to <a href="https://stackoverflow.com/questions/9899943/is-it-possible-to-use-non-imported-packages-in-a-package-vignette">this question</a> on Stack Overflow, adding these to the Suggests field ought to resolve the issue causing the note, but this doesn't seem to do so for me in this case. Can you recommend how you would address this note? If it is helpful, a link to the package is <a href="https://github.com/jrosen48/konfound" rel="nofollow noreferrer">here</a>.</p>