minor update to creating index on sharded cluster

Author: TylerBrock

source/administration/indexes.txt

@@ -265,10 +265,9 @@ on :term:`secondary` members of replica sets. The foreground index
 building process blocks all replication and read operations on the
 secondaries while they build the index.
 
-Secondaries will only begin building indexes *after* the
-:term:`primary` finishes building the index. All secondaries will
-build indexes at the same time. In :term:`sharded clusters <shard
-cluster>`, the :program:`mongos` will send :func:`ensureIndex()
+Secondaries will begin building indexes *after* the
+:term:`primary` finishes building the index. In :term:`sharded clusters
+<shard cluster>`, the :program:`mongos` will send :func:`ensureIndex()
 <db.collection.ensureIndex()>` to the primary members of the replica
 set for each shard, which then replicate to the secondaries after the
 primary finishes building the index.