Removed notice about additional GridFS

additional index was removed after discussion in #189

docs/source/NEWS.rst

@@ -13,8 +13,7 @@ Features
   empty password and ``mechanism="MONGODB-X509"``.
 - ``get_version()`` to approximate the behaviour of get_version in PyMongo. One noteable exception		
   is the omission of searching by random (unindexed) meta-data which should be considered a bad idea		
-  as it may create *very* variable conditions in terms of loading and timing. An additional index is		
-  also added to facilitate bi-directional movement between versions. Additional Unit test for GFS also added.
+  as it may create *very* variable conditions in terms of loading and timing.
 - New ``ConnectionPool.drop_database()`` method for easy and convenient destruction of all your precious data.
 - ``count()`` to return the number of versions of any given file in GridFS.