grammar/typo fix

Author: ablohowiak-fanhattan

source/reference/mongorestore.txt

@@ -14,7 +14,7 @@ dump, created by :program:`mongodump` into a specific
 database. :program:`mongorestore` can import content to an existing
 database or create a new one.
 
-:program:`mongorestore`, and only performs inserts into the existing
+:program:`mongorestore` only performs inserts into the existing
 database, and does not perform updates or :term:`upserts <upsert>`. If
 existing data with the same ``_id`` already exists on the target
 database, :program:`mongorestore` will *not* replace it.