title: Pure Prompt install issues
body: <p>I tried to install pure prompt for my terminal, but I don't think it has worked. Instead everytime I open terminal, I get this at the top:</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)
  
  Use prompt -h &lt;theme&gt; for help on specific themes.
  </code></pre>
  <p>Am I correct in thinking this is not supposed to show up? Also when I view all the themes, pure is not there. How should I resolve this?</p>
  <p>My .zshrc file contains the following:</p>
  <pre><code>setopt AUTO_CD
  # initialise nice autocompletion
  autoload -U compinit &amp;&amp; compinit
  
  # do not autoselect the first completion entry
  unsetopt MENU_COMPLETE
  unsetopt FLOW_CONTROL
  # show completion menu on successive tab press
  setopt AUTO_MENU
  setopt COMPLETE_IN_WORD
  setopt ALWAYS_TO_END
  
  # use a pretty menu to select options
  zstyle ':completion:*:*:*:*:*' menu select
  
  # initialize pure prompt
  autoload -U promptinit; promptinit
  prompt pure
  </code></pre>