edited my addition to pre-splits entry

Author: Bob Grabar

source/reference/glossary.txt

@@ -512,8 +512,8 @@ Glossary
       MongoDB will return from the documents in the result set.
 
    pre-splitting
-      Pre-splitting is a command run prior to data insertion that
-      specifies the shard key values on which to split up chunks.
+      Pre-splitting is an action you can perform prior to data insertion
+      that specifies the shard key values on which to split chunks.
       When deploying a :term:`shard cluster`, it is sometimes necessary
       to expedite the initial distribution of documents among shards by
       manually dividing the collection into chunks. In this case, you