title: Add a new row in specific place in a dataframe
body: <p>Heres my data:</p>
  
  <pre><code> &gt; data
    Manufacturers       Models
  1   Audi                RS5  
  2   BMW                 M3  
  3   Cadillac            CTS-V  
  4   Lexus               ISF
  </code></pre>
  
  <p>I would like to add 1 row in the fourth row, like this:</p>
  
  <pre><code> &gt; data
    Manufacturers       Models
  1   Audi                RS5  
  2   BMW                 M3  
  3   Cadillac            CTS-V  
  4   Benz                C63
  5   Lexus               ISF
  </code></pre>
  
  <p>I have tried to use the rbind() like this:</p>
  
  <pre><code> Benz = data.frame(Manufacturers = "Benz", Models = "C63")
   newdata = rbind(data,Benz)
  </code></pre>
  
  <p>But I cannot add to the place I want.
  I would appreciate any help on this question. Thanks a lot.</p>