minor: change to bucketSize index args documentation

Author: estolfo

pymongo/collection.py

@@ -752,8 +752,9 @@ def create_index(self, key_or_list, cache_for=300, **kwargs):
  - `dropDups` or `drop_dups`: should we drop duplicates
  - `background`: if this index should be created in the
  background
- - `bucketSize` or `bucket_size`: size of buckets for geoHaystack
- indexes during index creation when creating a unique index?
+ - `bucketSize` or `bucket_size`: for use with geoHaystack indexes.
+ Number of documents to group together within a certain proximity
+ to a given longitude and latitude.
  - `min`: minimum value for keys in a :data:`~pymongo.GEO2D`
  index
  - `max`: maximum value for keys in a :data:`~pymongo.GEO2D`
@@ -863,8 +864,9 @@ def ensure_index(self, key_or_list, cache_for=300, **kwargs):
  during index creation when creating a unique index?
  - `background`: if this index should be created in the
  background
- - `bucketSize` or `bucket_size`: size of buckets for geoHaystack
- indexes during index creation when creating a unique index?
+ - `bucketSize` or `bucket_size`: for use with geoHaystack indexes.
+ Number of documents to group together within a certain proximity
+ to a given longitude and latitude.
  - `min`: minimum value for keys in a :data:`~pymongo.GEO2D`
  index
  - `max`: maximum value for keys in a :data:`~pymongo.GEO2D`