fix typo (#3377)

Author: gmiller-mdb

source/reference/method/sh.shardCollection.txt

@@ -125,8 +125,8 @@ Definition
           initially when sharding an *empty* collection with a
           :ref:`hashed shard key <sharding-hashed-sharding>`. MongoDB
           then creates and balances chunks across the cluster. The
-          ``numInitialChunks`` must be less than ``8192`` per shard.
-          Defaults to ``2``.
+          ``numInitialChunks`` parameter must be less than ``8192`` chunks per shard.
+          Defaults to ``2`` chunks per shard.
 
           If the collection is not empty or the shard key does not
           contain a hashed field, the operation returns an error.