title: make new column based on presence of a word in another
body: <p>I have</p>
  
  <pre><code>pd.DataFrame({'text':['fewfwePDFerglergl','htrZIPg','gemlHTML']})
      text
  0   wePDFerglergl
  1   htrZIPg
  2   gemlHTML
  </code></pre>
  
  <p>a column 10k rows long. Each column contains one of ['PDF','ZIP','HTML']. The length of each entry in text is 14char max.</p>
  
  <p>how do I get:</p>
  
  <pre><code>pd.DataFrame({'text':['wePDFerglergl','htrZIPg','gemlHTML'],'file_type':['pdf','zip','html']})
      text            file_type
  0   wePDFerglergl   pdf
  1   htrZIPg         zip
  2   gemlHTML        html
  </code></pre>
  
  <p>I tried <code>df.text[0].find('ZIP')</code> for a single entry, but do not know how to stitch it all together to test and return the correct value for each row in the column</p>
  
  <p>Any suggestions?</p>