fix typo re2ad to read in write operations

Author: kay-kim

source/core/write-operations.txt

@@ -463,7 +463,7 @@ can cause the secondary's state to fall behind that of the primary. Secondaries
 that are significantly behind the primary present problems for normal
 operation of the replica set, particularly :ref:`failover
 <replica-set-failover-administration>` in the form of :ref:`rollbacks
-<replica-set-rollback>` as well as general :ref:`re2ad consistency
+<replica-set-rollback>` as well as general :ref:`read consistency
 <replica-set-consistency>`.
 
 To help avoid this issue, you can customize the :ref:`write concern