title: Unable to disable a startup message in Zsh
body: <p>I get the following when I start my Zsh.</p>
  
  <pre><code>Usage: prompt &lt;options&gt;
  Options:
      -c              Show currently selected theme and parameters
      -l              List currently available prompt themes
      -p [&lt;themes&gt;]   Preview given themes (defaults to all)
      -h [&lt;theme&gt;]    Display help (for given theme)
      -s &lt;theme&gt;      Set and save theme
      &lt;theme&gt;         Switch to new theme immediately (changes not saved)
  </code></pre>
  
  <p>It seems to be set by some theme file, since the same text is <a href="http://www.opensource.apple.com/source/zsh/zsh-48/zsh/Functions/Prompts/promptinit" rel="nofollow noreferrer">here</a>.</p>
  
  <p><strong>How can you disable the notification in Zsh?</strong></p>