title: scribble: how to remove "WARNING no declared exporting libraries"
body: <p>I'm trying to use <a href="http://docs.racket-lang.org/scribble/doc-forms.html#%28form._%28%28lib._scribble%2Fmanual..rkt%29._defproc%29%29" rel="noreferrer"><code>defproc</code></a> to format a function definition (<strong>not</strong> to document a library). The code below gets the formatting right, but prints an ugly warning to the console when I run Scribble:</p>
  
  <pre><code>#lang scribble/manual
  @require[(for-label racket/contract)]
  
  @defproc[(f [x integer?]) integer?]{
    The best @racket[f].
  }
  </code></pre>
  
  <p>Running <code>scribble --html example.scrbl</code> prints:</p>
  
  <pre><code>example.scrbl:4:10: WARNING: no declared exporting libraries for definition
    in: f
  </code></pre>
  
  <p>Is there any way to use <code>defproc</code> for formatting, and remove the error message?</p>