Minor typo

Author: puentesarrin

source/core/replication.txt

@@ -396,7 +396,7 @@ operations, (i.e. "read heavy") replica sets can greatly increase the
 capability of the database system.
 
 The minimum requirements for a replica set include two members with
-data, for a :term:`primary` and a secondary, and an :ref:`arbiters
+data, for a :term:`primary` and a secondary, and an :ref:`arbiter
 <replica-set-arbiters>`. In most circumstances, however, you will want
 to deploy three data members.