title: pandas.date_range custom frequency
body: <p>I'm trying to generate a list of dates that capture the 2nd day of the month using the pd.date_range for a rolling 12 month scenario. I don't quite know how to combine frequency alias in documentation to achieve this. Below is where I'm at and the output. I'd like to see </p>
  
  <pre><code>['2020-05-02', '2020-04-02', '2020-03-02'...]
  
  pd.date_range(end='2020-06-02',periods=12,freq=)
  
  DatetimeIndex(['2020-05-22', '2020-05-23', '2020-05-24', '2020-05-25',
                 '2020-05-26', '2020-05-27', '2020-05-28', '2020-05-29',
                 '2020-05-30', '2020-05-31', '2020-06-01', '2020-06-02'],
                dtype='datetime64[ns]', freq='D')
  </code></pre>