Duplicated bullet for zones

Merged two into one.

Author: asya999

source/core/workload-isolation.txt

@@ -59,19 +59,14 @@ documentation in the MongoDB Manual:
   control how applications create and interact with custom groupings
   of replica set members to create custom application-specific read
   preferences and write concerns.
-
-- :ref:`Zones <zone-sharding>` in sharded clusters, which allows MongoDB
-  administrators to create zones that represent a group of shards and
-  associate one or more ranges of :term:`shard key` values to that zone.
-  MongoDB routes reads and writes that fall into a zone range only to those
-  shards inside of the zone.
 
-- :ref:`Zones <zone-sharding>` in sharded clusters, which allows you to create
-  :term:`zones <zone>` of sharded data based on the :term:`shard key`. You can
-  associate each zone with one or more shards in the cluster. A shard can
-  associate with any number of non-conflicting zones. In a balanced cluster,
-  MongoDB directs reads and writes covered by a zone only to those shards
-  inside the zone.
+- :ref:`Zones <zone-sharding>` in sharded clusters, which allows MongoDB
+  administrators to create :term:`zones <zone>` that represent a group of 
+  shards and associate one or more ranges of :term:`shard key` values to
+  these zones. You can associate each zone with one or more shards in the 
+  cluster. A shard can associate with any number of zones. In a balanced 
+  cluster, MongoDB directs reads and writes covered by a zone only to the 
+  shards inside the zone.
 
 .. seealso::