title: DataFrame UserWarning with OR operator
body: <p>Python 3.6. I have the DataFrame warning :
  <code>UserWarning: This pattern has match groups. To actually get the groups, use str.extract.</code> 
  with this pattern :
  <code>laDataTemps.loc[laDataTemps['texte'].str.contains(r'\b(word1|word2)\b', regex=True)]</code></p>
  
  <p>Or, if i remove parenthesis to avoid groups, it won't have the same meaning. Any idea on how i could change the pattern to remove the warning ? Thanks !</p>