PYTHON-821 - Improve docs for write result acknowledged attribute.

Author: behackett

pymongo/results.py

@@ -33,7 +33,21 @@ def _raise_if_unacknowledged(self, property_name):
 
  @property
  def acknowledged(self):
- """Is this the result of an acknowledged write operation?"""
+ """Is this the result of an acknowledged write operation?
+
+ The :attr:`acknowledged` attribute will be ``False`` when using
+ ``WriteConcern(w=0)``, otherwise ``True``.
+
+ .. note::
+ If the :attr:`acknowledged` attribute is ``False`` all other
+ attibutes of this class will raise
+ :class:`~pymongo.errors.InvalidOperation` when accessed. Values for
+ other attributes cannot be determined if the write operation was
+ unacknowledged.
+
+ .. seealso::
+ :class:`~pymongo.write_concern.WriteConcern`
+ """
  return self.__acknowledged