text: Title: RequestOptions.auto_parse_qs_csv documentation is misleading for the True case
  Body: [`uri.parse_query_string`](https://falcon.readthedocs.io/en/stable/api/util.html#falcon.uri.parse_query_string) supports splitting parameter values on comma, however, only the first occurrence is actually split:
  ```python
  >>> uri.parse_query_string('interesting&stuff=1,2&key=value&stuff=3,4,5', csv=True)
  {'stuff': ['1', '2', '3,4,5'], 'key': 'value'}
  ```
  
  This is a known and documented limitation of `uri.parse_query_string`:
  > The two different ways of specifying lists may not be mixed in a single query string for the same parameter.
  
  However, documentation for [`RequestOptions.auto_parse_qs_csv`](https://falcon.readthedocs.io/en/stable/api/api.html#falcon.RequestOptions.auto_parse_qs_csv) mentions neither this limitation nor the fact that `uri.parse_query_string` is used for parsing. Moreover, it provides a misleading (although the example values are technically correct since only the first occurrence of `t` has commas) example:
  > When `auto_parse_qs_csv` is set to ``True``, the query string value
  > is also split on non-percent-encoded commas and these items
  > are added to the final list (i.e. ``/?t=1,2,3&t=4``
  > becomes ``['1', '2', '3', '4']``).