fixes errors in global term change (sharded clusters)

source/administration/backups.txt

@@ -18,7 +18,7 @@ process is crucial for every production-grade deployment. Take the
 specific features of your deployment, your use patterns, and
 architecture into consideration as you develop your own backup system.
 
-:term:`Replica sets <replica set>` and :term:`sharded clusters`
+:term:`Replica sets <replica set>` and :term:`sharded cluster`
 require special considerations. Don't miss the :ref:`backup
 considerations for sharded clusters and replica sets
 <backups-with-sharding-and-replication>`.

source/administration/replica-sets.txt

@@ -171,7 +171,7 @@ other members in the set will not advertise the hidden member in the
 
    .. versionchanged:: 2.0 
 
-   For :term:`sharded clusters` running with replica sets before 2.0 if
+   For :term:`sharded cluster` running with replica sets before 2.0 if
    you reconfigured a member as hidden, you *had* to restart
    :program:`mongos` to prevent queries from reaching the hidden
    member.

source/reference/glossary.txt

@@ -122,13 +122,6 @@ Glossary
 
       .. seealso:: The documents in the :doc:`/sharding` section of manual.
 
-   sharded cluster
-      The set of nodes comprising a :term:`sharded <sharding>` MongoDB deployment. A sharded cluster
-      consists of three config processes, one or more replica sets, and one or more
-      :program:`mongos` routing processes.
-
-      .. seealso:: The documents in the :doc:`/sharding` section of manual.
-
    partition
       A distributed system architecture that splits data into ranges.
       :term:`Sharding` is a kind of partitioning.

source/use-cases/pre-aggregated-reports.txt

@@ -555,7 +555,7 @@ Sharding
 --------
 
 The only potential limits on the performance of this system are the
-number of :term:`shards <shard>` in your :term:`system <shard
+number of :term:`shards <shard>` in your :term:`system <sharded
 cluster>`, and the :term:`shard key` that you use.
 
 .. pull-quote::