chore(dataframe_client): update param definition. Closes influxdata#525. (influxdata#819)

Author: sebito91

influxdb/_dataframe_client.py

@@ -59,6 +59,8 @@ def write_points(self,
  :param dataframe: data points in a DataFrame
  :param measurement: name of measurement
  :param tags: dictionary of tags, with string key-values
+ :param tag_columns: [Optional, default None] List of data tag names
+ :param field_columns: [Options, default None] List of data field names
  :param time_precision: [Optional, default None] Either 's', 'ms', 'u'
  or 'n'.
  :param batch_size: [Optional] Value to write the points in batches